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1
McQuaid, Conor, Andrea Halsey, Maëva Dubois, Ignacio Romero, and David Male. "Comparison of polypeptides that bind the transferrin receptor for targeting gold nanocarriers." PLOS ONE 16, no. 6 (June 4, 2021): e0252341. http://dx.doi.org/10.1371/journal.pone.0252341.
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The ability to target therapeutic agents to specific tissues is an important element in the development of new disease treatments. The transferrin receptor (TfR) is one potential target for drug delivery, as it expressed on many dividing cells and on brain endothelium, the key cellular component of the blood-brain barrier. The aim of this study was to compare a set of new and previously-described polypeptides for their ability to bind to brain endothelium, and investigate their potential for targeting therapeutic agents to the CNS. Six polypeptides were ranked for their rate of endocytosis by the human brain endothelial cell line hCMEC/D3 and the murine line bEnd.3. One linear polypeptide and two cyclic polypeptides showed high rates of uptake. These peptides were investigated to determine whether serum components, including transferrin itself affected uptake by the endothelium. One of the cyclic peptides was strongly inhibited by transferrin and the other cyclic peptide weakly inhibited. As proof of principle the linear peptide was attached to 2nm glucose coated gold-nanoparticles, and the rate of uptake of the nanoparticles measured in a hydrogel model of the blood-brain barrier. Attachment of the TfR-targeting polypeptide significantly increased the rates of endocytosis by brain endothelium and increased movement of nanoparticles across the cells.
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Evans, John Spencer, Ram Samudrala, Tiffany R. Walsh, Ersin Emre Oren, and Candan Tamerler. "Molecular Design of Inorganic-Binding Polypeptides." MRS Bulletin 33, no. 5 (May 2008): 514–18. http://dx.doi.org/10.1557/mrs2008.103.
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AbstractControlled binding and assembly of peptides onto inorganic substrates is at the core of bionanotechnology and biological-materials engineering. Peptides offer several unique advantages for developing future inorganic materials and systems. First, engineered polypeptides can molecularly recognize inorganic surfaces that are distinguishable by shape, crystallography, mineralogy, and chemistry. Second, polypeptides are capable of self-assembly on specific material surfaces leading to addressable molecular architectures. Finally, genetically engineered peptides offer multiple strategies for their functional modification. In this article, we summarize the details and mechanisms involved in combinatorial-polypeptide sequence selection and inorganic-material recognition and affinity, and outline experimental and theoretical approaches and concepts that will help advance this emerging field.
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Ibeanu, Nkiruka, Raphael Egbu, Lesley Onyekuru, Hoda Javaheri, Peng Tee Khaw, Gareth R. Williams, Steve Brocchini, and Sahar Awwad. "Injectables and Depots to Prolong Drug Action of Proteins and Peptides." Pharmaceutics 12, no. 10 (October 21, 2020): 999. http://dx.doi.org/10.3390/pharmaceutics12100999.
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Proteins and peptides have emerged in recent years to treat a wide range of multifaceted diseases such as cancer, diabetes and inflammation. The emergence of polypeptides has yielded advancements in the fields of biopharmaceutical production and formulation. Polypeptides often display poor pharmacokinetics, limited permeability across biological barriers, suboptimal biodistribution, and some proclivity for immunogenicity. Frequent administration of polypeptides is generally required to maintain adequate therapeutic levels, which can limit efficacy and compliance while increasing adverse reactions. Many strategies to increase the duration of action of therapeutic polypeptides have been described with many clinical products having been developed. This review describes approaches to optimise polypeptide delivery organised by the commonly used routes of administration. Future innovations in formulation may hold the key to the continued successful development of proteins and peptides with optimal clinical properties.
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Skelton, Nicholas J., Tamas Blandl, Stephen J. Russell, Melissa A. Starovasnik, and Andrea G. Cochran. "β‒hairpin polypeptides by design and selection." Spectroscopy 17, no. 2-3 (2003): 213–30. http://dx.doi.org/10.1155/2003/148024.
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We have developed polypeptide scaffolds that readily adopt aβ‒hairpin conformation (a pair of antiparallel strands connected by a turn) in solution. The study of such peptides allows us to understand the factors that govern stability and folding of these motifs in proteins, and permits mimicry of functionally important regions of proteins. Spectroscopic and biophysical methods have been used to characterize the conformational preferences and stability of these peptides, with a strong emphasis on using restraints generated from1H NMR spectroscopy to determine their three‒dimensional structure. By optimization of inter‒strand interactions, we have developed highly stable disulfide‒cyclized and linearβ‒hairpin peptides. In particular, tryptophan residues at non‒hydrogen bonded strand sites (NHB) are highly stabilizing. A variety of turn types have been presented from these scaffolds, suggesting that they might generally be useful in turn presentation. Interestingly,β‒hairpin peptides (containing a disulfide and a NHB tryptophan) have recently been discovered as antagonists of protein–protein interactions from naïve peptide libraries displayed on phage. Comparison of one suchβ‒hairpin peptide with anα‒helical peptide of very similar sequence provides further insight into the role that residue type and context play in determining polypeptide conformation.
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Fidelio, G. D., B. M. Austen, D. Chapman, and J. A. Lucy. "Properties of signal-sequence peptides at an air-water interface." Biochemical Journal 238, no. 1 (August 15, 1986): 301–4. http://dx.doi.org/10.1042/bj2380301.
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The surface behaviour of three signal-sequence polypeptides (the pretrypsinogen 2 signal sequence, a synthetic consensus signal sequence and the putative signal sequence of ovalbumin) were studied at an air-water interface. It was found that the surface stabilities of the spread polypeptide films were higher than those of polypeptides and proteins previously investigated (including melittin and membrane proteins), and that the signal peptides had a much lower affinity for the interface than had other peptides and proteins. The observed molecular areas of the signal-sequence peptides indicated that the molecules have a considerable degree of secondary structure at the surface interface.
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Xiong, Menghua, Michelle W. Lee, Rachael A. Mansbach, Ziyuan Song, Yan Bao, Richard M. Peek, Catherine Yao, et al. "Helical antimicrobial polypeptides with radial amphiphilicity." Proceedings of the National Academy of Sciences 112, no. 43 (October 12, 2015): 13155–60. http://dx.doi.org/10.1073/pnas.1507893112.
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α-Helical antimicrobial peptides (AMPs) generally have facially amphiphilic structures that may lead to undesired peptide interactions with blood proteins and self-aggregation due to exposed hydrophobic surfaces. Here we report the design of a class of cationic, helical homo-polypeptide antimicrobials with a hydrophobic internal helical core and a charged exterior shell, possessing unprecedented radial amphiphilicity. The radially amphiphilic structure enables the polypeptide to bind effectively to the negatively charged bacterial surface and exhibit high antimicrobial activity against both gram-positive and gram-negative bacteria. Moreover, the shielding of the hydrophobic core by the charged exterior shell decreases nonspecific interactions with eukaryotic cells, as evidenced by low hemolytic activity, and protects the polypeptide backbone from proteolytic degradation. The radially amphiphilic polypeptides can also be used as effective adjuvants, allowing improved permeation of commercial antibiotics in bacteria and enhanced antimicrobial activity by one to two orders of magnitude. Designing AMPs bearing this unprecedented, unique radially amphiphilic structure represents an alternative direction of AMP development; radially amphiphilic polypeptides may become a general platform for developing AMPs to treat drug-resistant bacteria.
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Chatterjee, Sunanda, Rituparna Sinha Roy, and P. Balaram. "Expanding the polypeptide backbone: hydrogen-bonded conformations in hybrid polypeptides containing the higher homologues of α-amino acids." Journal of The Royal Society Interface 4, no. 15 (January 23, 2007): 587–606. http://dx.doi.org/10.1098/rsif.2006.0203.
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Half a century has passed since the hydrogen-bonded secondary structures of polypeptides and proteins were first recognized. An extraordinary wealth of conformational information is now available on peptides and proteins, which are formed of α-amino acid residues. More recently, the discovery of well-folded structures in oligopeptides containing β-amino acids has focused a great deal of current interest on the conformational properties of peptides constructed from higher homologues (ω) of α-amino acids. This review examines the nature of intramolecularly hydrogen-bonded conformations of hybrid peptides formed by amino acid residues, with a varying number of backbone atoms. The β-turn, a ubiquitous structural feature formed by two residue (αα) segments in proteins and peptides, is stabilized by a 10-atom (C 10 ) intramolecular 4→1 hydrogen bond. Hybrid turns may be classified by comparison with their αα counterparts. The available crystallographic information on hydrogen-bonded hybrid turns is surveyed in this review. Several recent examples demonstrate that individual ω-amino acid residues and hybrid dipeptide segments may be incorporated into the regular structures of α-peptides. Examples of both peptide helices and hairpins are presented. The present review explores the relationships between folded conformations in hybrid sequences and their counterparts in all α-residue sequences. The use of stereochemically constrained ω-residues promises to expand the range of peptide design strategies to include ω-amino acids. This approach is exemplified by well-folded structures like the C 12 (αγ) and C 14 (γγ) helices formed in short peptides containing multiply substituted γ-residues. The achiral γ-residue gabapentin is a readily accessible building block in the design of peptides containing γ-amino acids. The construction of globular polypeptide structures using diverse hybrid sequences appears to be a realistic possibility.
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Nan, Nan, and Xi Jing Liu. "Study on Degradation of Radix Isatidis Polypeptide in Artificial Gastrointestinal Environment." Advanced Materials Research 989-994 (July 2014): 1020–24. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.1020.
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Radix Isatidis is a traditional Chinese medicine for treatment of influenza and inflammation in China. In this paper, in order to study the degradation situation of Radix Isatidis polypeptide in artificial gastrointestinal environment, the SDS-PAGE (Sodium dodecyl sulfate-polyacrylamide gel electrophoresis) method was used to detect the degradation of Radix Isatidis polypeptide in artificial intestinal juice and gastric juice, and it showed that Radix Isatidis peptides could be degradated to different degrees. HPLC (High Performance Liquid Chromatography) was used to determine the change of peptides degradation, and it indicated that free amino acid levels did not change significantly. The result after degradation was also detected by BCA method, and it showed that there were still a large number of polypeptides in the liquid. From this experiment we can come to this conclusion that Radix Isatidis polypeptides in artificial gastrointestinal juice mostly degraded into a series of different molecular weight peptides.
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Cole, D. G., W. Z. Cande, R. J. Baskin, D. A. Skoufias, C. J. Hogan, and J. M. Scholey. "Isolation of a sea urchin egg kinesin-related protein using peptide antibodies." Journal of Cell Science 101, no. 2 (February 1, 1992): 291–301. http://dx.doi.org/10.1242/jcs.101.2.291.
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To understand the roles of kinesin and its relatives in cell division, it is necessary to identify and characterize multiple members of the kinesin superfamily from mitotic cells. To this end we have raised antisera to peptides corresponding to highly conserved regions of the motor domains of several known members of the kinesin superfamily. These peptide antibodies react specifically with the motor domains of kinesin and ncd protein, as expected, and they also react with several polypeptides (including kinesin heavy chain) that cosediment with microtubules (MTs) precipitated from AMPPNP-treated sea urchin egg cytosol. Subsequent fractionation of ATP eluates of these MTs yields a protein of relative molecular mass 330 × 10(3) that behaves as a complex of three polypeptides that are distinct from conventional kinesin subunits or fragments thereof. This complex contains 85 kDa and 95 kDa polypeptides, which react with our peptide antibodies, and a 115 kDa polypeptide, which does not. This triplet of polypeptides, which we refer to as KRP(85/95), binds to purified sea urchin egg tubulin in an AMPPNP-enhanced, ATP-sensitive manner and induces the formation of microtubule bundles. We therefore propose that the triplet corresponds to a novel sea urchin egg kinesin-related protein.
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van Berkel, J., M. Steup, W. Völker, H. Robenek, and U. I. Flügge. "Polypeptides of the chloroplast envelope membranes as visualized by immunochemical techniques." Journal of Histochemistry & Cytochemistry 34, no. 5 (May 1986): 577–83. http://dx.doi.org/10.1177/34.5.3517143.
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The polypeptides of relative molecular masses (Mr) 22,000, 29,000, and 36,000 represent three major constituents of the chloroplast envelope of spinach (Spinacia oleracea L.) leaves. The Mr 22,000 polypeptide has been localized in the outer membrane, whereas the two other peptides have been attributed to the inner envelope membrane (Joyard et al., 1983). The Mr 29,000 polypeptide has been identified as the "phosphate translocator" (Flügge and Heldt, 1979). In this investigation, we studied the three envelope polypeptides by means of immunocytochemistry. Using indirect immunofluorescence, all three polypeptides were visualized in cryostat sections of formaldehyde-fixed leaf tissue. They were found in both palisade and spongy parenchyma cells and in guard cells, as indicated by a strong fluorescence in the chloroplast periphery. In contrast, fluorescein isothiocyanate or protein A-gold labeling of isolated fixed chloroplasts resulted only in visualization of the Mr 22,000 polypeptide, a constituent of the outer membrane. We further studied the morphological distribution and frequency of this peptide by electron microscopic evaluation of platinum-carbon replicas after freeze-etching or label-fracture and of ultra-thin sections. By use of these three methods, the polypeptide was found to be randomly distributed in the outer envelope membrane and easily accessible to the immunomarker. Average marker density, as obtained by freeze-etching and label-fracture, was approximately 130 gold particles per square micron.
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Gonçalves, Paloma, Francisco Martin, Patricia Borges, Maria Espirito Santo, Nuno Taveira, and José Marcelino. "PO 8597 NEUTRALISING AND NON-NEUTRALISING ANTIBODIES RESPONSE IN HIV-1-INFECTED INDIVIDUALS FROM MOZAMBIQUE." BMJ Global Health 4, Suppl 3 (April 2019): A61.2—A61. http://dx.doi.org/10.1136/bmjgh-2019-edc.161.
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BackgroundA vaccine that protects against the different HIV subtypes circulating around the world is essential to control and eliminate HIV infection. The immunogens are the key to develop an effective HIV vaccine. In this study, we characterised the antibody response against recombinant C2V3C3 polypeptides from several HIV-1 subtypes and evaluated the neutralising antibody response.MethodsPlasmas from HIV-1-infected individuals under treatment (n=39) and drugs-naïve individuals (n=8) were tested in an ELISA assay to determine the presence of antibodies against polypeptides from HIV-1 subtypes (CRF02_AG, B, C, G and H). The neutralising activity of plasma was evaluated with a panel of six HIV-1 viruses from a reference panel, [one tier 1 (NL4.3), and five tier 2 (PCH119_CRF07, PCE1176_C, TRO11_B, 246 F3_AC and CRF07_BJOX2000)] in a TZM-bl cells-based assay.ResultsOut of 48 plasmas, 44 (89.6%) reacted at least with one polypeptide and four (10.4%) did not react with any polypeptide. Interestingly, 56% of the plasmas recognise ≥3 peptides and 6 reacted with all polypeptides. The polypeptide from virus CRF02_AG was the most antigenic (77%) followed by the polypeptide C (58.3%), G (58.3%), H (50%) and B (35.4%). There was a positive correlation between polypeptides number recognised and binding antibody reactivity (r=0.4895, p=0.0111). All plasmas from drugs-naïve individuals neutralised at least one virus with neutralising activity between 39.3% and 95.7%. Four plasmas showed neutralising activity >50% against five viruses. The virus 249 F3 was the easiest to neutralise (median, 65.7%), whereas PCH119_CRF07 was the most difficult to neutralise (median, 43.6%). Neutralising activity of plasmas from patients under treatment are ongoing.ConclusionIn summary, these polypeptides could be useful in vaccine design once they are very antigenic and we observed a heterologous neutralising antibody response in naïve patients that expressed positive antibody-response anti-peptides.
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Lin, Rongcan, Yueqiao Wang, Xin Li, Yan Liu, and Yufen Zhao. "pH-Dependent Adsorption of Peptides on Montmorillonite for Resisting UV Irradiation." Life 10, no. 4 (April 20, 2020): 45. http://dx.doi.org/10.3390/life10040045.
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Ultraviolet (UV) irradiation is considered an energy source for the prebiotic chemical synthesis of life’s building blocks. However, it also results in photodegradation of biology-related organic compounds on early Earth. Thus, it is important to find a process to protect these compounds from decomposition by UV irradiation. Herein, pH effects on both the adsorption of peptides on montmorillonite (MMT) and the abilities of peptides to resist UV irradiation due to this adsorption were systematically studied. We found that montmorillonite (MMT) can adsorb peptides effectively under acidic conditions, while MMT-adsorbed peptides can be released under basic conditions. Peptide adsorption is positively correlated with the length of the peptide chains. MMT’s adsorption of peptides and MMT-adsorbed peptide desorption are both rapid-equilibrium, and it takes less than 30 min to reach the equilibrium in both cases. Furthermore, compared to free peptides, MMT-adsorbed peptides under acidic conditions are well protected from UV degradation even after prolonged irradiation. These results indicate amino acid/peptides are able to concentrate from aqueous solution by MMT adsorption under low-pH conditions (concentration step). The MMT-adsorbed peptides survive under UV irradiation among other unprotected species (storage step). Then, the MMT-adsorbed peptides can be released to the aqueous solution if the environment becomes more basic (releasing step), and these free peptides are ready for polymerization to polypeptides. Hence, a plausible prebiotic concentration–storage–release cycle of amino acids/peptides for further polypeptide synthesis is established.
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Snyder, H. L., J. W. Yewdell, and J. R. Bennink. "Trimming of antigenic peptides in an early secretory compartment." Journal of Experimental Medicine 180, no. 6 (December 1, 1994): 2389–94. http://dx.doi.org/10.1084/jem.180.6.2389.
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Major histocompatibility complex (MHC) class I molecules bind peptides of 8-10 residues in the endoplasmic reticulum (ER) and convey them to the cell surface for inspection by CD8-expressing T cells (TCD8+). Antigenic peptides are predominantly derived from a cytosolic pool of polypeptides. The proteolytic generation of peptides from polypeptides clearly begins in the cytosol, but it is uncertain whether the final proteolytic steps occur before or after peptides are transported into the ER by the MHC-encoded peptide transporter (TAP). To study the trimming of antigenic peptides in the secretory pathway in the absence of cytosolic processing, we used an NH2-terminal signal sequence to target to the ER of TAP-deficient cells, "tandem" peptides consisting of two defined TCD8+ determinants arranged from head to tail. We find that in contrast to cytosolic proteases in TAP-expressing cells, which are able to liberate antigenic peptides from either end of a tandem peptide, proteases (probably aminopeptidases) present in an early secretory compartment preferentially liberate the COOH-terminal determinant. These findings demonstrate that proteolytic activities associated with antigen processing are not limited to the cytosol, but that they also exist in an early secretory compartment. Such secretory aminopeptidases may function to trim TAP-transported peptides to the optimal size for binding to class I molecules.
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Ganapathy, V., and F. H. Leibach. "Carrier-mediated reabsorption of small peptides in renal proximal tubule." American Journal of Physiology-Renal Physiology 251, no. 6 (December 1, 1986): F945—F953. http://dx.doi.org/10.1152/ajprenal.1986.251.6.f945.
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Recent studies with a variety of tissue preparations in the kidney have demonstrated that proximal tubular cells possess specific transport systems for di- and tripeptides. In contrast to the well-known amino acid and glucose transport systems, active transport of peptides in these cells is energized by an H+ gradient rather than an Na+ gradient. Like amino acid-Na+ and glucose-Na+ cotransport systems, peptide-H+ cotransport is electrogenic and hence a membrane potential also contributes to the uphill transport of peptides in these cells. Di- and tripeptides that are filtered at the glomerulus, as well as those that are produced in the tubular lumen from larger polypeptides by the action of brush-border peptidases, serve as substrates for the renal peptide transport system under physiological conditions. The H+ gradient that is necessary to drive renal peptide transport is generated in vivo by concerted action of the basolateral Na+-K+-ATPase and the brush-border Na+-H+ exchanger. The peptidases and the peptide transport system in the renal brush-border membrane play a significant role in the reabsorption of peptide-bound amino acids as well as in the regulation of plasma levels of small peptides.
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Ahmed, Marya. "Peptides, polypeptides and peptide–polymer hybrids as nucleic acid carriers." Biomaterials Science 5, no. 11 (2017): 2188–211. http://dx.doi.org/10.1039/c7bm00584a.
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Boguszewska, A., R. Szyszka, and N. Grankowski. "The phosphorylation sites of ribosomal P proteins from Saccharomyces cerevisiae cells by endogenous CK-2, PK60S and RAP protein kinases." Acta Biochimica Polonica 44, no. 2 (June 30, 1997): 191–200. http://dx.doi.org/10.18388/abp.1997_4413.
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The phosphorylation sites of ribosomal acidic proteins (P proteins) from Saccharomyces cerevisiae were studied in vivo and in vitro by using CK-2, PK60S and RAP protein kinases. The three enzymes phosphorylate the last serine residues located in a highly conserved carboxyl end of the polypeptide chains. This was established by two-dimensional analysis of tryptic phosphopeptides from 32P-labelled proteins YP1 alpha, YP1 beta, YP2 alpha and YP2 beta, and by kinetic studies of the protein kinases with synthetic peptides corresponding to the fragments of endogenous ribosomal acidic polypeptides. In experiments with both endogenous P proteins and synthetic peptides as substrates protein kinase PK60S demonstrated unusual substrate specificity. In contrast to CK-2 and RAP protein kinases, PK60S phosphorylates predominantly two of the four P proteins, YP1 alpha and YP2 beta, with kinetic constants dependent on the primary structure of the N-terminal region of the polypeptide containing the target residue. The neutral amino acid, alanine, at position 3 in the peptide AAEESDDD (polypeptide fragments of YP1 beta and YP2 alpha) decreases the K(m) value more than 10-fold by comparison with the basic lysine residue at the same position in the peptide AKEESDDD (polypeptide fragments of YP1 alpha and YP2 beta).
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Wang, Tian-Tian, Yi-Yi Xia, Jian-Qing Gao, Dong-Hang Xu, and Min Han. "Recent Progress in the Design and Medical Application of In Situ Self-Assembled Polypeptide Materials." Pharmaceutics 13, no. 5 (May 19, 2021): 753. http://dx.doi.org/10.3390/pharmaceutics13050753.
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Inspired by molecular self-assembly, which is ubiquitous in natural environments and biological systems, self-assembled peptides have become a research hotspot in the biomedical field due to their inherent biocompatibility and biodegradability, properties that are afforded by the amide linkages forming the peptide backbone. This review summarizes the biological advantages, principles, and design strategies of self-assembled polypeptide systems. We then focus on the latest advances in in situ self-assembly of polypeptides in medical applications, such as oncotherapy, materials science, regenerative medicine, and drug delivery, and then briefly discuss their potential challenges in clinical treatment.
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Halila, R., M. Baumann, E. Ikonen, N. Enomaa, and L. Peltonen. "Human leucocyte aspartylglucosaminidase. Evidence for two different subunits in a more complex native structure." Biochemical Journal 276, no. 1 (May 15, 1991): 251–56. http://dx.doi.org/10.1042/bj2760251.
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Human leucocyte aspartylglucosaminidase (AGA: 1-aspartamido-beta-N-acetylglucosamine amidohydrolase, EC 3.5.1.26) was purified to homogeneity by using affinity chromatography, gel filtration, chromatofocusing and reverse-phase h.p.l.c. As shown by SDS/PAGE, the homogeneous purified enzyme preparation consists of four polypeptide chains with molecular masses of 25, 24, 18 and 17 kDa. In the native polyacrylamide gel these polypeptides migrate as one active enzyme complex, and by gel filtration the peak of enzyme activity can be detected in a position of about 65 kDa. Digestion with endoproteinase Lys-C or endoproteinase Asp-N, followed by peptide analysis with reverse-phase h.p.l.c., reveals an identical peptide pattern for the 24 and 25 kDa bands as well as for the 17 and 18 kDa bands. This treatment further demonstrated a totally different peptide pattern for the 24/25 kDa versus the 17/18 kDa subunit. The N-terminal sequences of the 17 kDa and the 18 kDa peptides were identical, as determined by Edman degradation. The N-termini of the 24 kDa and the 25 kDa peptides were blocked. The enzyme was partly resistant to endoglycosidases H and F, but N-glycosidase F transformed the 24/25 kDa band into one 23 kDa band and the 17/18 kDa band into one 16 kDa band. Also, immunological data obtained with antisera produced against these subunits showed that AGA consists of two non-identical polypeptides.
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Williams, G. D., and S. C. Holt. "Characteristics of the outer membrane of selected oral Bacteroides species." Canadian Journal of Microbiology 31, no. 3 (March 1, 1985): 238–50. http://dx.doi.org/10.1139/m85-046.
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The outer membranes from selected oral Bacteroides species were isolated and characterized morphologically, chemically, and physically. Both sucrose density gradient centrifugation and sodium dodecyl sulfate – polyacrylamide gel electrophoresis (SDS–PAGE) revealed outer membranes which varied slightly with the species, as well as showing complex polypeptide patterns after SDS–PAGE. The polypeptide distribution revealed a species-specific pattern; however, there was often a variation within a given species in many minor polypeptide bands, with heat-modifiable minor peptides occurring in nearly all species. Protein-associated carbohydrates occurred in several species. Outer membrane fragments (blebs) recovered by ultracentrifugation of the growth supernatants were either nearly identical to the outer membrane polypeptide patterns, or contained reduced amounts of specific polypeptides, again varying with the species. l25I-labelling of whole cells indicated possible surface exposure for several of the major polypeptides.
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Giménez, Luis G., Jose Rojas, Almudena Rojas, Joaquín Mendoza, and Ana G. Camacho. "Development of an Enzyme-Linked Immunosorbent Assay-Based Test with a Cocktail of Nucleocapsid and Spike Proteins for Detection of Severe Acute Respiratory Syndrome-Associated Coronavirus-Specific Antibody." Clinical and Vaccine Immunology 16, no. 2 (November 26, 2008): 241–45. http://dx.doi.org/10.1128/cvi.00252-08.
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ABSTRACT A new enzyme-linked immunosorbent assay (ELISA)-based immunoglobulin G (IgG)-plus-IgM antibody detection test for severe acute respiratory syndrome (SARS) has been developed by using a cocktail of four recombinant polypeptides as the antigen. These recombinant fragments were designed as parts of two different structural proteins from SARS-associated coronavirus (SARS-CoV). One recombinant polypeptide, S251-683, was designed as part of the spike glycoprotein, and the other three polypeptides comprised almost the whole nucleocapsid protein, avoiding the last 25 C-terminal amino acids. Immunization with a cocktail of these four polypeptides yielded a specific polyclonal antibody that is able to recognize SARS-CoV-infected cells by an immunofluorescence assay. This polypeptide cocktail was also used to set up an ELISA-based IgG-plus-IgM antibody detection test, which showed 99% specificity and 90% sensitivity upon evaluation using sera from 100 healthy negative controls and 20 SARS patients. Separate immunoreactivity assays with each recombinant polypeptide demonstrated that a combination of N and S protein fragments was more suitable than the individual peptides for developing a serological assay for SARS-CoV.
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Acharya, A., and V. Tripathi. "Novel Peptides Enhance the Production of Nitric Oxide and Inducible Nitric Oxide Synthase (iNOS) Gene Expression in Murine Macrophage." International Journal of Immunopathology and Pharmacology 16, no. 3 (September 2003): 241–46. http://dx.doi.org/10.1177/039463200301600309.
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Bioactive novel polypeptide of Anurans skin has a wide range of antimicrobial properties against the infection and tumour cell. Macrophages are known to produce the Nitric oxide (NO) by a variety of cells upon activation. NO produced by the activated macrophages an important mediator for antimicrobial and tumoricidal activity. In-vitro macrophage exposed with medium alone, containing LPS, containing polypepeptides and LPS + polypeptides for 24 h showed enhanced production of NO with respect to control and LPS treated and significant increase in NO production in LPS + polypeptide. Western blot and PCR analysis also showed that increased production of protein expression and mRNA expression of inducible nitric oxide synthase (iNOS). These findings suggest that novel polypeptides are potent activating agent for enhanced production of NO through activation of iNOS gene.
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Novoseletskaya, A. V., and Nina M. Kiseleva. "POSSIBLE MECHANISMS OF THYMUS PEPTIDES ANALGESIC ENDPOINT." Medical Journal of the Russian Federation 25, no. 1 (February 15, 2019): 44–48. http://dx.doi.org/10.18821/0869-2106-2019-25-1-44-48.
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Thymus polypeptides participate in stress-limiting system work. Considering that electropain stimulation is the main stress factor in many behavioral models, it is logical to assume that thymus polypeptides have analgesic activity. The objective of this research is study of opioid and serotoninergic systems role of thymus polypeptides analgesic endpoints implementation. The rats presented with tactivin and thymulin thymus peptides analgesic activity during tail withdrawal test, which is totally blocked by naloxone, and thus is based on opioid system activation. This effect is associated with appeared serotoninergic component of stress-induced analgesia. The possible mechanism of analgesic action and the role of serotoninergic system of thymus peptides were offered based on the results of the research conducted.
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Plancke, Yves, Béatrice Delpouve, and Jean Montreuil. "A solid phase assay for galactosyl transferases. Evidence for an active site of less than 14 kDa." Bioscience Reports 7, no. 9 (September 1, 1987): 721–29. http://dx.doi.org/10.1007/bf01116865.
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Galactosyltransferase (GalTase) prepared from human milk was found to exist as a complex with e-lactalbumin as demonstrated by crossed immunoelectrophoresis against specific antibodies raised against the complex. GalTase activity was stable to proteolysis and, when subjected to gel filtration on Ultrogel AcA54, the enzyme activity eluted as a single peak. A second peak of activity was found to be adsorbed to the column matrix and was eluted with buffer containing 1 M NaC1. The hydrophobic fraction represented 5% of the total GalTase activity in human milk. After polyacrylamide gel electrophoresis the main enzyme activity peak was represented by polypeptides of 67kDa molecular weight and of 14kDa molecular weight. Electroblotting of these peptides onto a nitrocellulose membrane followed by determination of GalTase activity showed activity for 45–55 kDa and for 14 kDa peptides. The hydrophobic fraction from the AcA54 column was resolved into polypeptides of 110 kDa-45 kDa molecular weight, all of which contained GalTase activity after blotting. It is supposed that the GalTase from non-proteolyzed milk is composed of a 14 kDa polypeptide containing the active site together with another part of the polypeptide backbone which is involved in the regulation of GalTase activity by α-lactalbumin, a third part of the polypeptide is responsible for the membrane insertion.
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WEI, JING, JIN-YUN WANG, MIN-YI ZHANG, GUO-LIANG CHAI, CHEN-SHENG LIN, and WEN-DAN CHENG. "A THEORETICAL STUDY ON SECOND HARMONIC GENERATION HYPERPOLARIZABILITIES OF PHENYLALANINE POLYPEPTIDES." Journal of Theoretical and Computational Chemistry 12, no. 02 (March 2013): 1250118. http://dx.doi.org/10.1142/s0219633612501180.
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The second harmonic generation (SHG) hyperpolarizabilities of phenylalanine and homopolypeptides are investigated by configuration interaction among singly excited configurations (CIS) technique combined with the sum-over-states (SOS) method. The geometries of peptides containing phenylalanine ( Phe )n(n = 1–8) are optimized by B3LYP/6-31g(d) method, and they form the special structures like β-sheet (a common protein secondary structure). It is found that the energy gaps of various peptides are reduced and the hyperpolarizabilities are increased with the peptide chains lengthened. We discuss the origin of the second-order nonlinear optical response in phenylalanine homopolypeptides and confirm that the π → π* transitions in the aromatic residue of phenylalanine make the most important contributions to the second-order polarizability. Our results strongly suggest that the hyperpolarizabilities are dominated from the propagation direction of peptide chains.
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Cociancich, S., A. Dupont, G. Hegy, R. Lanot, F. Holder, C. Hetru, J. A. Hoffmann, and P. Bulet. "Novel inducible antibacterial peptides from a hemipteran insect, the sap-sucking bug Pyrrhocoris apterus." Biochemical Journal 300, no. 2 (June 1, 1994): 567–75. http://dx.doi.org/10.1042/bj3000567.
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Insects belonging to the recent orders of the endopterygote clade (Lepidoptera, Diptera, Hymenoptera and Coleoptera) respond to bacterial challenge by the rapid and transient synthesis of a battery of potent antibacterial peptides which are secreted into their haemolymph. Here we present the first report on inducible antibacterial molecules in the sap-sucking bug Pyrrhocoris apterus, a representative species of the Hemiptera, which predated the Endoptergotes by at least 50 million years in evolution. We have isolated and characterized from immune blood of this species three novel peptides or polypeptides: (i) a 43-residue cysteine-rich anti-(Gram-positive bacteria) peptide which is a new member of the family of insect defensins; (ii) a 20-residue proline-rich peptide carrying an O-glycosylated substitution (N-acetylgalactosamine), active against Gram-negative bacteria; (iii) a 133-residue glycine-rich polypeptide also active against Gram-negative bacteria. The proline-rich peptide shows high sequence similarities with drosocin, an O-glycosylated antibacterial peptide from Drosophila, and also with the N-terminal domain of diptericin, an inducible 9 kDa antibacterial peptide from members of the order Diptera, whereas the glycine-rich peptide has similarities with the glycine-rich domain of diptericin. We discuss the evolutionary aspects of these findings.
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Leonard, Alex, and Piyush Koria. "Growth factor functionalized biomaterial for drug delivery and tissue regeneration." Journal of Bioactive and Compatible Polymers 32, no. 6 (May 5, 2017): 568–81. http://dx.doi.org/10.1177/0883911517705403.
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Elastin-like polypeptides are a class of naturally derived and non-immunogenic biomaterials that are widely used in drug delivery and tissue engineering. Elastin-like polypeptides undergo temperature-mediated inverse phase transitioning, which allows them to be purified in a relatively simple manner from bacterial expression hosts. Being able to genetically encode elastin-like polypeptides allows for the incorporation of bioactive peptides, thereby functionalizing them. Here, we report the synthesis of a biologically active epidermal growth factor–elastin-like polypeptide fusion protein that could aid in wound healing. Epidermal growth factor plays a crucial role in wound healing by inducing cell proliferation and migration. The use of exogenous epidermal growth factor has seen success in the treatment of acute wounds, but has seen relatively minimal success in chronic wounds because the method of delivery does not prevent it from diffusing away from the application site. Our data show that epidermal growth factor–elastin-like polypeptide retained the biological activity of epidermal growth factor and the phase transitioning property of elastin-like polypeptide. Furthermore, the ability of the epidermal growth factor–elastin-like polypeptide to self-assemble near physiological temperatures could allow for the formation of drug depots at the wound site and minimize diffusion, increasing the bioavailability of epidermal growth factor and enhancing tissue regeneration.
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Naik, Vaman M., and S. Krimm. "Vibrational analysis of peptides, polypeptides, and proteins." International Journal of Peptide and Protein Research 23, no. 1 (January 12, 2009): 1–24. http://dx.doi.org/10.1111/j.1399-3011.1984.tb02686.x.
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NAIK, V. M., S. KRIMM, J. B. DENTON, G. NÉMETHY, and H. A. SCHERAGA. "Vibrational analysis of peptides, polypeptides and proteins." International Journal of Peptide and Protein Research 24, no. 6 (January 12, 2009): 613–26. http://dx.doi.org/10.1111/j.1399-3011.1984.tb03168.x.
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BANDEKAR, JAGDEESH, and S. KRIMM. "Vibrational analysis of peptides, polypeptides, and proteins." International Journal of Peptide and Protein Research 26, no. 4 (January 12, 2009): 407–15. http://dx.doi.org/10.1111/j.1399-3011.1985.tb01007.x.
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BANDEKAR, JAGDEESH, and S. KRIMM. "Vibrational analysis of peptides, polypeptides, and proteins." International Journal of Peptide and Protein Research 26, no. 2 (January 12, 2009): 158–65. http://dx.doi.org/10.1111/j.1399-3011.1985.tb03192.x.
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Cockle, S. M., J. M. Morrell, and D. G. Smyth. "Thyrotrophin-releasing hormone-related polypeptides in rabbit prostate and semen are different from those in rabbit hypothalamus." Journal of Endocrinology 120, no. 1 (January 1989): 31–36. http://dx.doi.org/10.1677/joe.0.1200031.
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ABSTRACT TRH-related peptides were extracted from the hypothalamus and prostate gland of the rabbit. The peptides were fractionated by gel exclusion chromatography and located by trypsin digestion and radioimmunoassay with antibodies to TRH amide and TRH–Gly Lys. In the hypothalamus TRH-related peptides containing approximately 16 and 30 residues were observed: in these peptides the extensions to the TRH sequence were exclusively in the C-terminal direction. In addition, the three-residue form of TRH was also present. In the prostate complex, the predominant TRH-related peptide contained approximately 50 residues and the extension to the TRH tripeptide was on the N-terminal side; a three-residue form of immunoreactive TRH was also demonstrated. The same pattern of TRH-related peptides was shown to be present in rabbit semen. The results reveal the existence of a novel TRH-related polypeptide in the prostate and semen which does not occur in the hypothalamus. This peptide appears to undergo secretion. Journal of Endocrinology (1989) 120, 31–36
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Hermand, P., I. Mouro, M. Huet, C. Bloy, K. Suyama, J. Goldstein, JP Cartron, and P. Bailly. "Immunochemical characterization of rhesus proteins with antibodies raised against synthetic peptides." Blood 82, no. 2 (July 15, 1993): 669–76. http://dx.doi.org/10.1182/blood.v82.2.669.669.
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Abstract Rabbit polyclonal antibodies were raised against synthetic peptides corresponding to hydrophilic regions of the human Rhesus (Rh) IX cDNA- encoded polypeptide predicted to be extracellularly or intracellularly exposed in the topologic model of the Rh blood group protein. Four antibodies encompassing residues 33–45 (MPC1), 224–233 (MPC4), 390–404 (MPC6), and 408–416 (MPC8) were characterized and compared with a polyclonal anti-Rh protein obtained by immunization with purified Rh proteins. All antibodies had specificity for authentic Rh polypeptides and reacted on Western blot with Rh proteins immunoprecipitated with human monoclonal anti-RhD, -c, and -E. MPC1, but not the other antibodies, agglutinated all human erythrocytes except Rhnull and Rhmod cells, which either lack totally or are severely deficient in Rh proteins, respectively. Immunoblotting analysis with membrane proteins from common and rare variants showed that MPC1 and MPC8 reacted in Western blot with 32-Kd Rh polypeptides from all common red blood cells except those from Rhnull and Rhmod, indicating that peptide regions 33– 45 and 408–416 may be common to several if not all Rh proteins, whatever the Rh blood group specificity. MPC4 reacted only with membrane preparations from cells carrying the E antigen, whereas MPC6 recognized preferentially the Rh proteins from E and Ee preparations, suggesting that the protein encoded by the RhIXb cDNA carries the E and/or e antigen(s). Immunoadsorption experiments using inside-out or right-side-out sealed vesicules from DccEE red blood cells as competing antigen showed that the MPC6 and MPC8 antibodies bound only to the cytoplasmic side of the erythrocyte membrane, thus providing evidence for the intracellular orientation of the C-terminal 27 residues of the Rh polypeptides. Attempts to transiently or stably express the Rh polypeptides. Attempts to transiently or stably express the Rh cDNA in eukaryotic cells were largely unsuccessful, suggesting that Rh antigen expression at the cell surface requires correct transport and/or folding of the Rh proteins, possibly as a complex with one-membrane proteins of the Rh cluster that are lacking in Rhnull cells.
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Hermand, P., I. Mouro, M. Huet, C. Bloy, K. Suyama, J. Goldstein, JP Cartron, and P. Bailly. "Immunochemical characterization of rhesus proteins with antibodies raised against synthetic peptides." Blood 82, no. 2 (July 15, 1993): 669–76. http://dx.doi.org/10.1182/blood.v82.2.669.bloodjournal822669.
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Rabbit polyclonal antibodies were raised against synthetic peptides corresponding to hydrophilic regions of the human Rhesus (Rh) IX cDNA- encoded polypeptide predicted to be extracellularly or intracellularly exposed in the topologic model of the Rh blood group protein. Four antibodies encompassing residues 33–45 (MPC1), 224–233 (MPC4), 390–404 (MPC6), and 408–416 (MPC8) were characterized and compared with a polyclonal anti-Rh protein obtained by immunization with purified Rh proteins. All antibodies had specificity for authentic Rh polypeptides and reacted on Western blot with Rh proteins immunoprecipitated with human monoclonal anti-RhD, -c, and -E. MPC1, but not the other antibodies, agglutinated all human erythrocytes except Rhnull and Rhmod cells, which either lack totally or are severely deficient in Rh proteins, respectively. Immunoblotting analysis with membrane proteins from common and rare variants showed that MPC1 and MPC8 reacted in Western blot with 32-Kd Rh polypeptides from all common red blood cells except those from Rhnull and Rhmod, indicating that peptide regions 33– 45 and 408–416 may be common to several if not all Rh proteins, whatever the Rh blood group specificity. MPC4 reacted only with membrane preparations from cells carrying the E antigen, whereas MPC6 recognized preferentially the Rh proteins from E and Ee preparations, suggesting that the protein encoded by the RhIXb cDNA carries the E and/or e antigen(s). Immunoadsorption experiments using inside-out or right-side-out sealed vesicules from DccEE red blood cells as competing antigen showed that the MPC6 and MPC8 antibodies bound only to the cytoplasmic side of the erythrocyte membrane, thus providing evidence for the intracellular orientation of the C-terminal 27 residues of the Rh polypeptides. Attempts to transiently or stably express the Rh polypeptides. Attempts to transiently or stably express the Rh cDNA in eukaryotic cells were largely unsuccessful, suggesting that Rh antigen expression at the cell surface requires correct transport and/or folding of the Rh proteins, possibly as a complex with one-membrane proteins of the Rh cluster that are lacking in Rhnull cells.
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Wang, Lan, Qian Liu, Jin-Chun Chen, Yi-Xian Cui, Bing Zhou, Yong-Xiang Chen, Yu-Fen Zhao, and Yan-Mei Li. "Antimicrobial activity of human islet amyloid polypeptides: an insight into amyloid peptides’ connection with antimicrobial peptides." Biological Chemistry 393, no. 7 (July 1, 2012): 641–46. http://dx.doi.org/10.1515/hsz-2012-0107.
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Abstract Human islet amyloid polypeptide (hIAPP) shows an antimicrobial activity towards two types of clinically relevant bacteria. The potency of hIAPP varies with its aggregation states. Circular dichroism was employed to determine the interaction between hIAPP and bacteria lipid membrane mimic. The antimicrobial activity of each aggregate species is associated with their ability to induce membrane disruption. Our findings provide new evidence revealing the antimicrobial activity of amyloid peptide, which suggest a possible connection between amyloid peptides and antimicrobial peptides.
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Niedermann, Gabriele, Rudolf Grimm, Elke Geier, Martina Maurer, Claudio Realini, Christoph Gartmann, Jürgen Soll, et al. "Potential Immunocompetence of Proteolytic Fragments Produced by Proteasomes before Evolution of the Vertebrate Immune System." Journal of Experimental Medicine 186, no. 2 (July 21, 1997): 209–20. http://dx.doi.org/10.1084/jem.186.2.209.
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To generate peptides for presentation by major histocompatibility complex (MHC) class I molecules to T lymphocytes, the immune system of vertebrates has recruited the proteasomes, phylogenetically ancient multicatalytic high molecular weight endoproteases. We have previously shown that many of the proteolytic fragments generated by vertebrate proteasomes have structural features in common with peptides eluted from MHC class I molecules, suggesting that many MHC class I ligands are direct products of proteasomal proteolysis. Here, we report that the processing of polypeptides by proteasomes is conserved in evolution, not only among vertebrate species, but including invertebrate eukaryotes such as insects and yeast. Unexpectedly, we found that several high copy ligands of MHC class I molecules, in particular, self-ligands, are major products in digests of source polypeptides by invertebrate proteasomes. Moreover, many major dual cleavage peptides produced by invertebrate proteasomes have the length and the NH2 and COOH termini preferred by MHC class I. Thus, the ability of proteasomes to generate potentially immunocompetent peptides evolved well before the vertebrate immune system. We demonstrate with polypeptide substrates that interferon γ induction in vivo or addition of recombinant proteasome activator 28α in vitro alters proteasomal proteolysis in such a way that the generation of peptides with the structural features of MHC class I ligands is optimized. However, these changes are quantitative and do not confer qualitatively novel characteristics to proteasomal proteolysis. The data suggest that proteasomes may have influenced the evolution of MHC class I molecules.
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Aili, D., K. Enander, L. Baltzer, and B. Liedberg. "Synthetic de novo designed polypeptides for control of nanoparticle assembly and biosensing." Biochemical Society Transactions 35, no. 3 (May 22, 2007): 532–34. http://dx.doi.org/10.1042/bst0350532.
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This contribution describes how de novo designed synthetic helix–loop–helix polypeptides are utilized to control the assembly of gold nanoparticles and as scaffolds for biosensing. The synthetic polypeptides are designed to fold into a four-helix bundle upon dimerization. When immobilized on gold nanoparticles, dimerization and folding occur between peptides on neighbouring particles as an effect of particle aggregation and the folded polypeptides are rigid enough to keep the particles separated at a distance corresponding to the size of the four-helix bundle. Moreover, peptide dimerization offers a convenient route to assemble nanoparticles into hybrid multilayers on planar substrates. The drastic change in the resonance conditions of the localized nanoparticle surface plasmon upon particle aggregation is shown to be useful for optical detection of biomolecular interactions.
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Canepa, Carlo. "On the chemical diversity of the prebiotic ocean of early Earth." International Journal of Astrobiology 14, no. 3 (December 1, 2014): 497–504. http://dx.doi.org/10.1017/s1473550414000688.
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AbstractThis work investigates the consequences on the diverse number of chemical species in a pre-biotic terrestrial aqueous environment endowed with an amino acid source induced by the spontaneous build-up of catalytically active polypeptides from amino acid monomers. The assumed probability that a randomly formed polypeptide exhibits catalytic properties is dependent on constraining both the chemical identity and the position of a fraction of the amino acid residues. Within this hypothesis, and using values of the average length n of the catalytic polypeptides about one half of the present-day enzymes, the stationary-state concentration of the catalytically active polypeptides is ≈10−30 −10−19 M, and the ratio of the concentration of a product of a catalytic process to the initial concentration of the corresponding substrate is predicted to be ≈10−6−105. Matching the mean life of each catalytic polypeptide to the mean life of its substrate (λ ≈ ω) is only possible by significantly raising the intensity of the source of the amino acid monomers. Under these hypothetical optimal conditions, the mean lives of the catalytic polypeptides and their substrates have values ω−1 ≈ λ−1 ≈10 yr and the asymptotic concentration of each product is of the same order of magnitude as the concentration of the substrate. In all cases the catalytic efficiency necessary to form the active peptides takes the typical values of present-day enzymes.
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Dong, Na, Chensi Wang, Xinran Li, Yuming Guo, and Xiaoli Li. "Simplified Head-to-Tail Cyclic Polypeptides as Biomaterial-Associated Antimicrobials with Endotoxin Neutralizing and Anti-Inflammatory Capabilities." International Journal of Molecular Sciences 20, no. 23 (November 25, 2019): 5904. http://dx.doi.org/10.3390/ijms20235904.
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The therapeutic application of antimicrobial peptides (AMPs), a potential type of peptide-based biomaterial, is impeded by their poor antimicrobial activity and potential cytotoxicity as a lack of understanding of their structure–activity relationships. In order to comprehensively enhance the antibacterial and clinical application potency of AMPs, a rational approach was applied to design amphiphilic peptides, including head-to-tail cyclic, linear and D-proline antimicrobial peptides using the template (IR)nP(IR)nP (n = 1, 2 and 3). Results showed that these amphiphilic peptides demonstrated antimicrobial activity in a size-dependent manner and that cyclic peptide OIR3, which contained three repeating units (IR)3, had greater antimicrobial potency and cell selectivity than liner peptide IR3, DIR3 with D-Pro and gramicidin S (GS). Surface plasmon resonance and endotoxin neutralization assays indicated that OIR3 had significant endotoxin neutralization capabilities, which suggested that the effects of OIR3 were mediated by binding to lipopolysaccharides (LPS). Using fluorescence spectrometry and electron microscopy, we found that OIR3 strongly promoted membrane disruption and thereby induced cell lysis. In addition, an LPS-induced inflammation assay showed that OIR3 inhibited the pro-inflammatory factor TNF-α in RAW264.7 cells. OIR3 was able to reduce oxazolone-induced skin inflammation in allergic dermatitis mouse model via the inhibition of TNF-α, IL-1β and IL-6 mRNA expression. Collectively, the engineered head-to-tail cyclic peptide OIR3 was considerable potential candidate for use as a clinical therapeutic for the treatment of bacterial infections and skin inflammation.
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Tsuchiya, Kousuke, and Keiji Numata. "Facile terminal functionalization of peptides by protease-catalyzed chemoenzymatic polymerization toward synthesis of polymeric architectures consisting of peptides." Polymer Chemistry 11, no. 2 (2020): 560–67. http://dx.doi.org/10.1039/c9py01335k.
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Weinberger, Barry, Nazeeh Hanna, Jeffrey D. Laskin, Diane E. Heck, Carol R. Gardner, Donald R. Gerecke, and Debra L. Laskin. "Mechanisms Mediating the Biologic Activity of Synthetic Proline, Glycine, and Hydroxyproline Polypeptides in Human Neutrophils." Mediators of Inflammation 2005, no. 1 (2005): 31–38. http://dx.doi.org/10.1155/mi.2005.31.
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The accumulation of neutrophils at sites of tissue injury or infection is mediated by chemotactic factors released as part of the inflammatory process. Some of these factors are generated as a direct consequence of tissue injury or infection, including degradation fragments of connective tissue collagen and bacterial- or viral-derived peptides containing collagen-related structural motifs. In these studies, we examined biochemical mechanisms mediating the biologic activity of synthetic polypeptides consisting of repeated units of proline (Pro), glycine (Gly), and hydroxyproline (Hyp), major amino acids found within mammalian and bacterial collagens. We found that the peptides were chemoattractants for neutrophils. Moreover, their chemotactic potency was directly related to their size and composition. Thus, the pentameric peptides (Pro-Pro-Gly)and (Pro-Hyp-Gly)were more active in inducing chemotaxis than the corresponding decameric peptides (Pro-Pro-Gly)and (Pro-Hyp-Gly). In addition, the presence of Hyp in peptides reduced chemotactic activity. The synthetic peptides were also found to reduce neutrophil apoptosis. In contrast to chemotaxis, this activity was independent of peptide size or composition. The effects of the peptides on both chemotaxis and apoptosis were blocked by inhibitors of phosphatidylinositol 3-kinase (PI3-K) and p38 mitogen-activated protein (MAP) kinase. However, only (Pro-Pro-Gly)and (Pro-Pro-Gly)induced expression of PI3-K and phosphorylation of p38 MAP kinase, suggesting a potential mechanism underlying reduced chemotactic activity of Hyp-containing peptides. Although none of the synthetic peptides tested had any effect on intracellular calcium mobilization, each induced nuclear binding activity of the transcription factor NF-κB. These findings indicate that polymeric polypeptides containing Gly-X-Y collagen-related structural motifs promote inflammation by inducing chemotaxis and blocking apoptosis. However, distinct calcium-independent signaling pathways appear to be involved in these activities.
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CHEN, Jingxiao, Huiyuan WANG, Xiaoding XU, Weihai CHEN, and Xianzheng ZHANG. "PEPTIDES AND POLYPEPTIDES FOR GENE AND DRUG DELIVERY." Acta Polymerica Sinica 011, no. 8 (August 19, 2011): 799–811. http://dx.doi.org/10.3724/sp.j.1105.2011.11100.
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SADAT-AALAEE, D. "ChemInform Abstract: Chemical Synthesis of Peptides and Polypeptides." ChemInform 29, no. 4 (June 24, 2010): no. http://dx.doi.org/10.1002/chin.199804281.
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Voß, R., A. Radunz, and G. H. Schmid. "Binding of Lipids onto Polypeptides of the Thylakoid Membrane I. Galactolipids and Sulpholipid as Prosthetic Groups of Core Peptides of the Photosystem II Complex." Zeitschrift für Naturforschung C 47, no. 5-6 (June 1, 1992): 406–15. http://dx.doi.org/10.1515/znc-1992-0615.
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Photosystem II complexes were prepared from chloroplasts of wild type tobacco Nicotiana tabacum var. John William’s Broadleaf and from two chlorophyll mutants derived from it, namely N. tabacum Su/su and N. tabacum Su/su var. Aurea. The hydrophobic peptides of these complexes were analyzed for bound lipid molecules by means of monospecific lipid antisera. A comparison of the peptide composition of the complexes of the three chloroplast types by means of polyacrylamide gel electrophoresis showed that the peptide composition was qualitatively identical. A major quantitative difference referred to a 66 kDa peptide which appeared to be much stronger in gels of photosystem II peptides originating from the yellowgreen and the yellow tobacco variety. Furthermore, we were able to show that different SDS polyacrylamide gel electrophoresis runs of the same PS II preparation yielded differences in the band strength of this peptide. Comparative densitometric measurements showed that an increase in this 66 kDa peptide was always correlated with a decrease in the D1 and D2 peptides. Obviously, the 66 kDa peptide is the heterodimer of D1 and D2. Differences in the peptide composition of photosystem II preparations from the 3 tobacco species refer above all to peptides of the light-harvesting complex with molecular masses of 28 and 26 kDa. After the transfer of the peptides from the polyacrylamide gel to nitrocellulose membranes, they were incubated with monospecific antisera to monogalactolipid, digalactolipid or sulfolipid. These experiments showed that the 66 kDa peptide reacted with antibodies to digalactolipid and with those to sulfolipid. The 66 kDa peptide reacts in the Western blot procedure also with an antiserum to a 66 kDa peptide prepared and characterized earlier and which was shown to inhibit electron transport reactions in the region of the reaction center of photosystem II. The monospecific antiserum to monogalactolipid reacts with the D1 and D2 peptide as well as with the chlorophyll-binding polypeptides of the masses 42 and 48 kDa, and also with the 26 and 28 kDa peptides of the light-harvesting complex as well as with the extrinsic peptides exhibiting the molecular masses, 33 ,21 -23 and 18 kDa. Whereas lipase treatment apparently destroys the lipids as antigenic determinants of the peptides on the nitrocellulose membrane, periodate treatment or treatment of the photosystem II preparations with organic solvents do not prevent the reaction of the 66 kDa peptide with the sulfolipid antiserum. These experiments show as the 66 kDa peptide appears to be the heterodimer of D1 and D2, that the galactolipids mono- and digalactosyldiglyceride as well as the sulfolipid are bound, much like prosthetic groups, onto the core peptides.
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Michel, André G., Chakib Ameziane-Hassani, and Nathalie Bredin. "Low-energy conformational domains of polypeptides, characterized by a random-search and minimization procedure." Canadian Journal of Chemistry 70, no. 2 (February 1, 1992): 596–603. http://dx.doi.org/10.1139/v92-083.
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In the framework of molecular mechanics conformational energy calculations, a random-search and minimization procedure is presented to characterize low-energy domains of polypeptidic structures. Rather than striving for global minima, populations of conformers are randomly generated, and their energy is minimized in order to study their intrinsic properties. The application to the opioid peptide Met-Enkephalin allowed the identification of low-energy domains that are compared with previous results of conformational studies on this molecule. Our method gives a complete overview of the conformational behaviour of the polypeptide under study, including previously reported structures as determined from experimental and theoretical studies. To illustrate the usefulness of this method to determine bioactive peptidic structures and their active conformers, the application to geometrically constrained chemotactic tripeptides is presented. Keywords: peptides, conformation, theoretical prediction.
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Rabideau, Amy E., Xiaoli Liao, and Bradley L. Pentelute. "Delivery of mirror image polypeptides into cells." Chemical Science 6, no. 1 (2015): 648–53. http://dx.doi.org/10.1039/c4sc02078b.
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Defenouillère, Quentin, Abdelkader Namane, John Mouaikel, Alain Jacquier, and Micheline Fromont-Racine. "The ribosome-bound quality control complex remains associated to aberrant peptides during their proteasomal targeting and interacts with Tom1 to limit protein aggregation." Molecular Biology of the Cell 28, no. 9 (May 2017): 1165–76. http://dx.doi.org/10.1091/mbc.e16-10-0746.
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Protein quality control mechanisms eliminate defective polypeptides to ensure proteostasis and to avoid the toxicity of protein aggregates. In eukaryotes, the ribosome-bound quality control (RQC) complex detects aberrant nascent peptides that remain stalled in 60S ribosomal particles due to a dysfunction in translation termination. The RQC complex polyubiquitylates aberrant polypeptides and recruits a Cdc48 hexamer to extract them from 60S particles in order to escort them to the proteasome for degradation. Whereas the steps from stalled 60S recognition to aberrant peptide polyubiquitylation by the RQC complex have been described, the mechanism leading to proteasomal degradation of these defective translation products remains unknown. We show here that the RQC complex also exists as a ribosome-unbound complex during the escort of aberrant peptides to the proteasome. In addition, we identify a new partner of this light version of the RQC complex, the E3 ubiquitin ligase Tom1. Tom1 interacts with aberrant nascent peptides and is essential to limit their accumulation and aggregation in the absence of Rqc1; however, its E3 ubiquitin ligase activity is not required. Taken together, these results reveal new roles for Tom1 in protein quality control, aggregate prevention, and, therefore, proteostasis maintenance.
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Reyes, A. A., R. Akeson, L. Brezina, and G. J. Cole. "Structural requirements for neural cell adhesion molecule-heparin interaction." Cell Regulation 1, no. 8 (July 1990): 567–76. http://dx.doi.org/10.1091/mbc.1.8.567.
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Two biological domains have been identified in the amino terminal region of the neural cell adhesion molecule (NCAM): a homophilic-binding domain, responsible for NCAM-NCAM interactions, and a heparin-binding domain (HBD). It is not known whether these two domains exist as distinct structural entities in the NCAM molecule. To approach this question, we have further defined the relationship between NCAM-heparin binding and cell adhesion. A putative HBD consisting of two clusters of basic amino acid residues located close to each other in the linear amino acid sequence of NCAM has previously been identified. Synthetic peptides corresponding to this domain were shown to bind both heparin and retinal cells. Here we report the construction of NCAM cDNAs with targeted mutations in the HBD. Mouse fibroblast cells transfected with the mutant cDNAs express NCAM polypeptides with altered HBD (NCAM-102 and NCAM-104) or deleted HBD (HBD-) at levels similar to those of wild-type NCAM. Mutant NCAM polypeptides purified from transfected cell lines have substantially reduced binding to heparin and fail to promote chick retinal cell attachment. Furthermore, whereas a synthetic peptide that contains both basic amino acid clusters inhibits retinal-cell adhesion to NCAM-coated dishes, synthetic peptides in which either one of the two basic regions is altered to contain only neutral amino acids do not inhibit this adhesion. These results confirm that this region of the NCAM polypeptide does indeed mediate not only the large majority of NCAM's affinity for heparin but also a significant portion of the cell-adhesion-mediating capability of NCAM.
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Williams, Kristina M., Elmer C. Bigley, and Richard B. Raybourne. "Identification of Murine B-Cell and T-Cell Epitopes of Escherichia coli Outer Membrane Protein F with Synthetic Polypeptides." Infection and Immunity 68, no. 5 (May 1, 2000): 2535–45. http://dx.doi.org/10.1128/iai.68.5.2535-2545.2000.
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ABSTRACT The major pore-forming outer membrane proteins (Omps) of gram-negative bacteria demonstrate numerous immunomodulating properties and are involved in the virulence of pathogenic strains. BecauseEscherichia coli OmpF is the best-characterized porin in terms of structural and functional characteristics, in vitro B-cell and T-cell responses to this porin in six different strains of mice were analyzed. Mice were immunized with purified OmpF trimers or overlapping synthetic polypeptides (20-mers) spanning the entire 340-amino-acid sequence of the OmpF monomer. T-cell proliferative responses and immunoglobulin G antibody responses to native OmpF and the peptide analogues were determined. For each strain, patterns of T-cell proliferation were similar regardless of whether native OmpF or synthetic peptides were inoculated, although all strains recognized one or more cryptic determinants. Mice exhibited several haplotype-specific responses, but genetically permissive epitopes were also identified. Four peptides (75-94, 265-284, 295-314, and 305-324) elicited strong T-cell proliferative responses from all strains of mice when mice were presensitized with native OmpF or a homologous peptide. In general, 10 or fewer peptides were recognized by sera from mice immunized with native OmpF or synthetic peptides, and most sera from peptide-immunized mice reacted poorly with the native protein. Four peptides spanning amino acids 45 to 64, 95 to 114, 115 to 134, and 275 to 294 were recognized by sera from all strains immunized with native OmpF but not by sera from peptide-immunized mice. Peptides 245-264 and 305-324 were universally recognized by sera from peptide-immunized mice, but these sera reacted weakly or were negative when tested against the native protein. Based on the pattern of cytokine secretion by proliferating T cells, immunization with native OmpF polarizes T helper cells toward development of a TH1 response. T-cell and B-cell responses have been investigated based on the assumption that differences in epitope specificity could influence protective or pathologic host reactions. Because of the high level of structural homology of OmpF to porins isolated from other enteric pathogens, the identification of T- and B-cell-stimulatory determinants of E. coli OmpF may have broader application.
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Paschal, B. M., A. Mikami, K. K. Pfister, and R. B. Vallee. "Homology of the 74-kD cytoplasmic dynein subunit with a flagellar dynein polypeptide suggests an intracellular targeting function." Journal of Cell Biology 118, no. 5 (September 1, 1992): 1133–43. http://dx.doi.org/10.1083/jcb.118.5.1133.
Full textAbstract:
In previous work we found cytoplasmic dynein to be a complex of two catalytic heavy chains and at least seven co-purifying polypeptides of unknown function. The most prominent of these is a 74-kD electrophoretic species which can be resolved as two to three bands by SDS-PAGE. We have now selected a series of overlapping rat brain cDNAs encoding the 74-kD species. The deduced sequence of a full-length cDNA predicts a 72,753 D polypeptide which includes the amino acid sequences of nine peptides determined by NH2-terminal microsequencing. PCR performed on first strand rat brain cDNA together with the sequence of a partially matching tryptic peptide indicated the existence of at least three isoforms of the 74-kD cytoplasmic dynein subunit. Comparison with known sequences revealed that the carboxyl-terminal half of the polypeptide is 26.4% identical and 47.7% similar to the product of the Chlamydomonas ODA6 gene, a 70-kD intermediate chain of flagellar outer arm dynein. Immunoblot analysis with a monoclonal antibody to the 74-kD species indicated a widespread tissue distribution, as expected for a cytoplasmic dynein subunit. Nonetheless, the antibody recognized a 67-kD species in ram sperm flagella and pig tracheal cilia, supporting the existence of distinct but related cytoplasmic and axonemal polypeptides in mammals. In view of evidence for a role for the ODA6 gene product in anchoring flagellar dynein to the A subfiber microtubule in the axoneme, we predict an analogous role for the 74-kD polypeptide, perhaps in mediating the interaction of cytoplasmic dynein with membranous organelles and kinetochores.
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Panchamoorthy, G., T. Fukazawa, L. Stolz, G. Payne, K. Reedquist, S. Shoelson, Z. Songyang, L. Cantley, C. Walsh, and H. Band. "Physical and functional interactions between SH2 and SH3 domains of the Src family protein tyrosine kinase p59fyn." Molecular and Cellular Biology 14, no. 9 (September 1994): 6372–85. http://dx.doi.org/10.1128/mcb.14.9.6372.
Full textAbstract:
The Src family protein tyrosine kinases participate in signalling through cell surface receptors that lack intrinsic tyrosine kinase domains. All nine members of this family possess adjacent Src homology (SH2 and SH3) domains, both of which are essential for repression of the enzymatic activity. The repression is mediated by binding between the SH2 domain and a C-terminal phosphotyrosine, and the SH3 domain is required for this interaction. However, the biochemical basis of functional SH2-SH3 interaction is unclear. Here, we demonstrate that when the SH2 and SH3 domains of p59fyn (Fyn) were present as adjacent domains in a single protein, binding of phosphotyrosyl peptides and proteins to the SH2 domain was enhanced, whereas binding of a subset of cellular polypeptide ligands to the SH3 domain was decreased. An interdomain communication was further revealed by occupancy with domain-specific peptide ligands: occupancy of the SH3 domain with a proline-rich peptide enhanced phosphotyrosine binding to the linked SH2 domain, and occupancy of the SH2 domain with phosphotyrosyl peptides enhanced binding of certain SH3-specific cellular polypeptides. Second, we demonstrate a direct binding between purified SH2 and SH3 domains of Fyn and Lck Src family kinases. Heterologous binding between SH2 and SH3 domains of closely related members of the Src family, namely, Fyn, Lck, and Src, was also observed. In contrast, Grb2, Crk, Abl, p85 phosphatidylinositol 3-kinase, and GTPase-activating protein SH2 domains showed lower or no binding to Fyn or Lck SH3 domains. SH2-SH3 binding did not require an intact phosphotyrosine binding pocket on the SH2 domain; however, perturbations of the SH2 domain induced by specific high-affinity phosphotyrosyl peptide binding abrogated binding of the SH3 domain. SH3-SH2 binding was observed in the presence of proline-rich peptides or when a point mutation (W119K) was introduced in the putative ligand-binding pouch of the Fyn SH3 domain, although these treatments completely abolished the binding to p85 phosphatidylinositol 3-kinase and other SH3-specific polypeptides. These biochemical SH2-SH3 interactions suggest novel mechanisms of regulating the enzymatic activity of Src kinases and their interactions with other proteins.