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Journal articles on the topic 'Tyrosine fluorescence'

Author: Grafiati

Published: 4 June 2021

Last updated: 17 February 2022

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1

Turner, R. J., R. S. Roche, R. S. Mani, and C. M. Kay. "Tyrosine and tyrosinate fluorescence of S-100b. A time-resolved nanosecond fluorescence study. The effect of pH, Ca(II), and Zn(II)." Biochemistry and Cell Biology 67, no. 4-5 (April 1, 1989): 179–86. http://dx.doi.org/10.1139/o89-028.

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The properties of the tyrosine and tyrosinate emissions from brain S-100b have been studied by nanosecond time-resolved fluorescence at emission wavelengths in the range 305 to 365 nm. The effect of pH on the fluorescence has been studied at pH 6.5, 7.5, and 8.5 for the Ca(II) apo and holo forms of the protein, and for the apo and holo forms in the presence and absence of Zn(II) at pH 7.5. The fluorescence decay is biexponential at pH 8.5 and triexponential at pH 6.5 and 7.5. The three components of the decay have wavelength and metal ion dependent lifetimes in the ranges 0.06 to 1.05 ns, 0.49 to 3.76 ns, and 3.60 to 14.5 ns. The observation of a long lifetime component at wavelengths characteristic of emission from tyrosinate suggests that in class A proteins this may be a useful diagnostic of the environment of tyrosine in their native structures. The time-resolved emission spectra provide evidence for efficient, subnanosecond protolysis of the excited state of the single tyrosine (Tyr17) under all conditions studied except in 6 M guanidium chloride in which the protein shows only emission from tyrosine (λem 305 nm), suggesting that the tyrosinate emission is a property of the tertiary structure of the native protein. The Zn(II)-dependence of the fluorescence is fully consistent with the earlier suggestion that Tyr17 is near the Zn(II) binding site and remote from the high affinity Ca(II) binding site.Key words: S-100b, time-resolved fluorescence, tyrosinate fluorescence, time-resolved emission spectra.

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2

O'Neil, J. D. J., and T. Hofmann. "Tyrosine and tyrosinate fluorescence of pig intestinal Ca2+-binding protein." Biochemical Journal 243, no. 2 (April 15, 1987): 611–15. http://dx.doi.org/10.1042/bj2430611.

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The single tyrosine residue in both pig and cow intestinal Ca2+-binding proteins fluoresces at 303 nm although the crystal structure of the cow protein shows a hydrogen bond between the hydroxy group of the tyrosine and glutamate-38 [Szebenyi & Moffat (1986) J. Biol. Chem. 261, 8761-8777]. The latter interaction suggests that tyrosinate fluorescence should dominate the emission spectra of these proteins. A fluorescence difference spectrum, produced by subtracting the spectrum of free tyrosine from the spectrum of the protein, gives a peak at 334 nm due to ionized tyrosine. That this component of the emission spectrum is not due to a tryptophan-containing contaminant is shown by its elimination when the protein is denatured by guanidine and when glutamate-38 is protonated. We conclude that, in solution, the tyrosine residue in this protein interacts occasionally with glutamate-38 but that a permanent hydrogen bond is not formed.

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3

Shen, Yiming, Deyi Zhu, Wenhui Lu, Bing Liu, Yanchun Li, and Shan Cao. "The Characteristics of Intrinsic Fluorescence of Type I Collagen Influenced by Collagenase I." Applied Sciences 8, no. 10 (October 16, 2018): 1947. http://dx.doi.org/10.3390/app8101947.

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The triple helix structure of collagen can be degraded by collagenase. In this study, we explored how the intrinsic fluorescence of type I collagen was influenced by collagenase I. We found that tyrosine was the main factor that could successfully excite the collagen fluorescence. Initially, self-assembly behavior of collagen resulted in a large amount of tyrosine wrapped with collagen, which decreased the fluorescence intensity of type I collagen. After collagenase cleavage, some wrapped-tyrosine could be exposed and thereby the intrinsic fluorescence intensity of collagen increased. By observation and analysis, the influence of collagenase to intrinsic fluorescence of collagen was investigated and elaborated. Furthermore, collagenase cleavage to the special triple helix structure of collagen would result in a slight improvement of collagen thermostability, which was explained by the increasing amount of terminal peptides. These results are helpful and effective for reaction mechanism research related to collagen, which can be observed by fluorescent technology. Meantime, the reaction behaviors of both collagenase and collagenolytic proteases can also be analyzed by fluorescent technology. In conclusion, this research provides a foundation for the further investigation of collagen reactions in different areas, such as medicine, nutrition, food and agriculture.

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4

Gahn, L. G., and R. Roskoski. "Tyrosine hydroxylase activity and extrinsic fluorescence changes produced by polyanions." Biochemical Journal 295, no. 1 (October 1, 1993): 189–94. http://dx.doi.org/10.1042/bj2950189.

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The activity of tyrosine hydroxylase in vitro is affected by many factors, including pH, phosphorylation by several protein kinases, and polyanions. We investigated the activation of tyrosine hydroxylase by RNA or DNA (polyanions), using purified rat PC12 cell enzyme. RNA and DNA each increased tyrosine hydroxylase activity in the presence of subsaturating (125 microM) tetrahydrobiopterin at pH 6. RNA increased enzyme activity up to 6-fold with an EC50 of 3 micrograms/ml. RNA and DNA each increased tyrosine hydroxylase activity by decreasing the Km of the enzyme for tetrahydrobiopterin from 3 mM to 295 microM in the presence of 100 micrograms/ml RNA or 171 microM in the presence of 100 micrograms/ml DNA. We used the apolar fluorescent probe 8-anilino-1-naphthalenesulphonic acid (1,8-ANS) as a reporter group to provide the first evidence for changes in conformation related to changes in activity. At pH 6.0, 1,8-ANS bound to tyrosine hydroxylase and exhibited a characteristic fluorescence spectrum. At pH 7.2, both enzyme activity and fluorescence decreased. DNA or heparin (another polyanion) activated tyrosine hydroxylase and decreased fluorescence of the reporter group 30% at pH 6.0. This decrease suggests that these polyanions altered the conformation of tyrosine hydroxylase. The activating effects of polyanions were diminished at physiological pH (6.8-7.2) or in the presence of bivalent-cation salts (10 mM) or univalentcation salts (100 mM). These results suggest that polyanions play a minimal role, if any, in the physiological regulation of tyrosine hydroxylase activity.

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5

Willis, K. J., and A. G. Szabo. "Fluorescence decay kinetics of tyrosinate and tyrosine hydrogen-bonded complexes." Journal of Physical Chemistry 95, no. 4 (February 1991): 1585–89. http://dx.doi.org/10.1021/j100157a015.

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6

Jiang, Chao, Ya Li, Chenghui Liu, Liying Qiu, and Zhengping Li. "A general and versatile fluorescence turn-on assay for detecting the activity of protein tyrosine kinases based on phosphorylation-inhibited tyrosyl oxidation." Chemical Communications 52, no. 85 (2016): 12570–73. http://dx.doi.org/10.1039/c6cc07035c.

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7

WANG, Jing-Dong, Shuang LI, Rong LÜ, and An-Chi YU. "Fluorescence Quenching of Eosin Y by Tyrosine." Acta Physico-Chimica Sinica 31, no. 9 (2015): 1787–94. http://dx.doi.org/10.3866/pku.whxb201507241.

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8

Seethala, Ramakrishna. "Fluorescence Polarization Competition Immunoassay for Tyrosine Kinases." Methods 22, no. 1 (September 2000): 61–70. http://dx.doi.org/10.1006/meth.2000.1037.

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9

Gavrilov, V. B., A. V. Lychkovskii, E. P. Shostak, and S. V. Konev. "Fluorescence assay of tyrosine in blood plasma." Journal of Applied Spectroscopy 65, no. 3 (May 1998): 379–84. http://dx.doi.org/10.1007/bf02675456.

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10

Tominaga, Tania Toyomi, Hidetake Imasato, Otaciro Rangel Nascimento, and Marcel Tabak. "Interaction of tyrosine and tyrosine dipeptides with Cu2+ ions: A fluorescence study." Analytica Chimica Acta 315, no. 1-2 (October 1995): 217–24. http://dx.doi.org/10.1016/0003-2670(95)00303-h.

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11

Pritz, Stephan, Gabriele Meder, Klaus Doering, Peter Drueckes, Julian Woelcke, Lorenz M. Mayr, and Ulrich Hassiepen. "A Fluorescence Lifetime-Based Assay for Abelson Kinase." Journal of Biomolecular Screening 16, no. 1 (December 8, 2010): 65–72. http://dx.doi.org/10.1177/1087057110385817.

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We present a novel homogeneous in vitro assay format and apply it to the quantitative determination of the enzymatic activity of a tyrosine kinase. The assay employs a short peptidic substrate containing a single tyrosine and a single probe attached via a cysteine side chain. The structural flexibility of the peptide allows for the dynamic quenching of the probe by the nonphosphorylated tyrosine side chain. The probe responds with changes in its fluorescence lifetime depending on the phosphorylation state of the tyrosine. We use this effect to directly follow the enzymatic phosphorylation of the substrate, without having to resort to additional assay components such as an antibody against the phosphotyrosine. As an example for the application of this assay principle, we present results from the development of an assay for Abelson kinase (c-Abl) used for compound profiling. Adjustments in the peptide sequence would make this assay format suitable to a wide variety of other tyrosine kinases.

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12

Murphy, Timothy V., Brian E. Spurrell, and Michael A. Hill. "Tyrosine phosphorylation following alterations in arteriolar intraluminal pressure and wall tension." American Journal of Physiology-Heart and Circulatory Physiology 281, no. 3 (September 1, 2001): H1047—H1056. http://dx.doi.org/10.1152/ajpheart.2001.281.3.h1047.

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Arterioles respond to increased transmural pressure with myogenic constriction. The present study investigated the role of tyrosine phosphorylation in myogenic activity. Cannulated segments of a rat cremaster arteriole were fixed under pressure, followed by incubation with fluorescein isothiocyanate (FITC)-conjugated anti-phosphotyrosine. Smooth muscle cell fluorescence intensity was measured with the use of confocal laser-scanning microscopy. Anti-phosphotyrosine fluorescence intensity in muscle cells of arterioles maintained at 100 mmHg was reduced by the tyrosine kinase inhibitor tyrphostin A47 (30 μM) and increased by the tyrosine phosphatase inhibitor pervanadate (100 μM). In time-course experiments, anti-phosphotyrosine fluorescence increased slowly (over 5 min) after an acute increase in intraluminal pressure, and was dissociated from myogenic contraction (within 1 min). In contrast, angiotensin II (0.1 μM) caused rapid constriction and increased tyrosine phosphorylation. Anti-phosphotyrosine fluorescence was also pressure dependent (10–100 mmHg). Abolition of myogenic activity, either through removal of extracellular Ca2+, or exposure to verapamil (5 μM) or forskolin (0.1 μM) caused a further increase in anti-phosphotyrosine fluorescence. We conclude that transmural pressure and/or wall tension in arterioles causes increased tyrosine phosphorylation; however, this is not involved in the acute phase of myogenic constriction but may be involved in later responses, such as sustained myogenic tone or mechanisms possibly related to growth.

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13

Chen, Bo-Han, Chen-Chu Wang, Lu-Yi Lu, Kuo-Sheng Hung, and Yuh-Shyong Yang. "Fluorescence assay for protein post-translational tyrosine sulfation." Analytical and Bioanalytical Chemistry 405, no. 4 (November 18, 2012): 1425–29. http://dx.doi.org/10.1007/s00216-012-6540-3.

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14

Amaro, Mariana, David J. S. Birch, and Olaf J. Rolinski. "Beta-amyloid oligomerisation monitored by intrinsic tyrosine fluorescence." Physical Chemistry Chemical Physics 13, no. 14 (2011): 6434. http://dx.doi.org/10.1039/c0cp02652b.

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15

Leon, Leonardo J., Cindy C. Pratt, Lesley J. Vasquez, and Paul M. M. Weers. "Tyrosine fluorescence analysis of apolipophorin III–lipopolysaccharide interaction." Archives of Biochemistry and Biophysics 452, no. 1 (August 2006): 38–45. http://dx.doi.org/10.1016/j.abb.2006.05.009.

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16

Ci, Yun-Xiang, Lie Chen, and Shan Wei. "Peroxidase-catalysed fluorescence reaction using tyrosine as substrate." Fresenius' Zeitschrift für analytische Chemie 332, no. 3 (January 1988): 258–60. http://dx.doi.org/10.1007/bf00492972.

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17

Seethala, Ramakrishna, and Rolf Menzel. "A Fluorescence Polarization Competition Immunoassay for Tyrosine Kinases." Analytical Biochemistry 255, no. 2 (January 1998): 257–62. http://dx.doi.org/10.1006/abio.1997.2455.

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18

Goldberg, Jacob M., Rebecca F. Wissner, Alyssa M. Klein, and E. James Petersson. "Thioamide quenching of intrinsic protein fluorescence." Chemical Communications 48, no. 10 (2012): 1550–52. http://dx.doi.org/10.1039/c1cc14708k.

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19

Laws, William R., J. B. Alexander Ross, Herman R. Wyssbrod, Joseph M. Beechem, Ludwig Brand, and John Clark Sutherland. "Time-resolved fluorescence and proton NMR studies of tyrosine and tyrosine analogs: correlation of NMR-determined rotamer populations and fluorescence kinetics." Biochemistry 25, no. 3 (February 11, 1986): 599–607. http://dx.doi.org/10.1021/bi00351a013.

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20

KRETZSCHMAR, Antje K., Michaela C. DINGER, Christian HENZE, Katja BROCKE-HEIDRICH, and Friedemann HORN. "Analysis of Stat3 (signal transducer and activator of transcription 3) dimerization by fluorescence resonance energy transfer in living cells." Biochemical Journal 377, no. 2 (January 15, 2004): 289–97. http://dx.doi.org/10.1042/bj20030708.

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Signal transducer and activator of transcription 3 (Stat3) dimerization is commonly thought to be triggered by its tyrosine phosphorylation in response to interleukin-6 (IL-6) or other cytokines. Accumulating evidence from in vitro studies, however, suggests that cytoplasmic Stat3 may be associated with high-molecular-mass protein complexes and/or dimerize prior to its activation. To directly study Stat3 dimerization and subcellular localization upon cytokine stimulation, we used live-cell fluorescence spectroscopy and imaging microscopy combined with fluorescence resonance energy transfer (FRET). Stat3 fusion proteins with spectral variants of green fluorescent protein (GFP), cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) were constructed and expressed in human hepatoma cells (HepG2) and human embryonic kidney cells (HEK-293). Like wild-type Stat3, the fusion proteins redistributed from a preferentially cytoplasmic to nuclear localization upon IL-6 stimulation and supported IL-6-dependent target gene expression. FRET studies in cells co-expressing Stat3–CFP and Stat3–YFP demonstrated that Stat3 dimers exist in the absence of tyrosine phosphorylation. IL-6 induced a 2-fold increase of this basal FRET signal, indicating that tyrosine phosphorylation either increases the dimer/monomer ratio of Stat3 or induces a conformational change of the dimer yielding a higher FRET efficiency. Studies using a mutated Stat3 with a non-functional src-homology 2 (SH2) domain showed that the SH2 domain is essential for dimer formation of phosphorylated as well as non-phosphorylated Stat3. Furthermore, our data show that visualization of normalized FRET signals allow insights into the spatiotemporal dynamics of Stat3 signal transduction.

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21

Sen, Tirthendu, Anastasia Mamontova, Anastasia Titelmayer, Aleksander Shakhov, Artyom Astafiev, Atanu Acharya, Konstantin Lukyanov, Anna Krylov, and Alexey Bogdanov. "Influence of the First Chromophore-Forming Residue on Photobleaching and Oxidative Photoconversion of EGFP and EYFP." International Journal of Molecular Sciences 20, no. 20 (October 22, 2019): 5229. http://dx.doi.org/10.3390/ijms20205229.

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Enhanced green fluorescent protein (EGFP)—one of the most widely applied genetically encoded fluorescent probes—carries the threonine-tyrosine-glycine (TYG) chromophore. EGFP efficiently undergoes green-to-red oxidative photoconversion (“redding”) with electron acceptors. Enhanced yellow fluorescent protein (EYFP), a close EGFP homologue (five amino acid substitutions), has a glycine-tyrosine-glycine (GYG) chromophore and is much less susceptible to redding, requiring halide ions in addition to the oxidants. In this contribution we aim to clarify the role of the first chromophore-forming amino acid in photoinduced behavior of these fluorescent proteins. To that end, we compared photobleaching and redding kinetics of EGFP, EYFP, and their mutants with reciprocally substituted chromophore residues, EGFP-T65G and EYFP-G65T. Measurements showed that T65G mutation significantly increases EGFP photostability and inhibits its excited-state oxidation efficiency. Remarkably, while EYFP-G65T demonstrated highly increased spectral sensitivity to chloride, it is also able to undergo redding chloride-independently. Atomistic calculations reveal that the GYG chromophore has an increased flexibility, which facilitates radiationless relaxation leading to the reduced fluorescence quantum yield in the T65G mutant. The GYG chromophore also has larger oscillator strength as compared to TYG, which leads to a shorter radiative lifetime (i.e., a faster rate of fluorescence). The faster fluorescence rate partially compensates for the loss of quantum efficiency due to radiationless relaxation. The shorter excited-state lifetime of the GYG chromophore is responsible for its increased photostability and resistance to redding. In EYFP and EYFP-G65T, the chromophore is stabilized by π-stacking with Tyr203, which suppresses its twisting motions relative to EGFP.

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22

Maeno, Akihiro, Hiroshi Matsuo, and Kazuyuki Akasaka. "Tyrosine/tyrosinate fluorescence at 700MPa: A pressure unfolding study of chicken ovomucoid at pH12." Biophysical Chemistry 183 (December 2013): 57–63. http://dx.doi.org/10.1016/j.bpc.2013.07.008.

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23

Liu, Wen, Liankai Zhang, Pengyu Liu, Xiaoqun Qin, Xiaojing Shan, and Xin Yao. "FDOM Conversion in Karst Watersheds Expressed by Three-Dimensional Fluorescence Spectroscopy." Water 10, no. 10 (October 11, 2018): 1427. http://dx.doi.org/10.3390/w10101427.

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A karst system, formed by the dissolution of carbonate rocks, is usually susceptible to contamination. Little is known about the composition of natural dissolved organic matter (DOM) in groundwater systems, especially in karstic groundwater. To reveal the characteristics of DOM in a karst aquifer, the Yufuhe River Basin, a typical karst watershed in northern China, was selected. DOM fluorescence (FDOM) was measured with the excitation-emission matrices (EEMs) spectroscopy technique. Parallel factor analysis (PARAFAC) was used to analyze the karst hydrogeological factors that affect FDOM biogeochemical behavior. Three fluorescent components, i.e., tyrosine-like, tryptophan-like, and ultraviolet fulvic acid were found. Their fluorescence properties were closely related to human activity and subterranean hydrology. Fluorescence properties suggested that FDOM in the Yufuhe River karst aquifer was predominant from anthropogenic activity. In addition, due to the effect of karstic heterogeneous hydrological conditions, FDOM showed obvious differentiation in the recharge, flow path, and discharge systems. The FDOM fluorescence intensity (FI) was weak in surface water and groundwater at the upper reaches (recharge area). In the middle of the flow path area, the percentage of tyrosine-like and tryptophan-like substances degraded and fulvic acid rose gradually. However, after infiltrating into the lower reaches (discharge area) of the deep karst aquifer system, the fulvic acid matter was consumed and protein-like matter accumulated.

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24

Hosono, K., T. Ueno, H. Taguchi, H. Motojima, T. Zako, M. Yoshida, and T. Funatsu. "1L1615 Conformational Change of GroEL Studied by Tyrosine Fluorescence." Seibutsu Butsuri 42, supplement2 (2002): S72. http://dx.doi.org/10.2142/biophys.42.s72_1.

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25

Samuels, Alan C., James O. Jensen, and Hendrik F. Hameka. "Theoretical studies of the fluorescence and phosphorescence of tyrosine." Journal of Molecular Structure: THEOCHEM 454, no. 1 (December 1998): 25–30. http://dx.doi.org/10.1016/s0166-1280(98)00195-x.

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26

Kolb, Alfred J., Paul V. Kaplita, David J. Hayes, Young-Whan Park, Christine Pernell, John S. Major, and Gérard Mathis. "Tyrosine kinase assays adapted to homogeneous time-resolved fluorescence." Drug Discovery Today 3, no. 7 (July 1998): 333–42. http://dx.doi.org/10.1016/s1359-6446(98)01204-5.

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27

Lohmann, W., Ch Lohmann, and M. Ibrahim. "Fluorescence spectra of NADH/NAD, kynurenine, tryptophan, and tyrosine." Naturwissenschaften 75, no. 3 (March 1988): 141–42. http://dx.doi.org/10.1007/bf00405305.

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28

Sakhi, Alina, and Josef Lazar. "Observing Tyrosine Kinase Function by Polarization Resolved Fluorescence Microscopy." Biophysical Journal 120, no. 3 (February 2021): 327a. http://dx.doi.org/10.1016/j.bpj.2020.11.2061.

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29

Meibaum, Jörn, Silvie Krause, Hartmut Hillmer, Daniele Marcelli, and Christof Strohhöfer. "Identification and characterisation of fluorescent substances in spent dialysis fluid." International Journal of Artificial Organs 43, no. 9 (February 4, 2020): 579–86. http://dx.doi.org/10.1177/0391398820901826.

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Patients who suffer from end-stage renal disease require renal replacement therapy, including haemodialysis. While applying extracorporeal blood treatment, uraemic toxins accumulated in the patients’ blood pass into a physiological solution, the dialysis fluid. Thus, important information about the patient’s health status can be obtained by analysing the spent dialysis fluid. To make use of this information, corresponding analysis concepts must be developed. In this context, this article reports the analysis of fluorescence in spent dialysis fluid. Excitation and emission maxima of fluorescence in spent dialysis fluid were recorded, and the main fluorescent substances were identified and quantified using high-performance liquid chromatography analysis. Fluorescence in spent dialysis fluid has two prominent excitation maxima at λex1 = 228 nm and λex2 = 278 nm. However, both excitation maxima cause emission with maxima at λem = 350 nm. Identification of fluorescent substances using high-performance liquid chromatography showed that the main contributors to the overall fluorescence in spent dialysis fluid are tyrosine, tryptophan, indoxyl sulphate and indole-3-acetic acid. However, these substances are responsible for only one-third of the overall fluorescence of spent dialysis fluid. A large number of substances, each of which contributes only to a small part to the overall fluorescence, emit the remaining fluorescence.

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30

Das, Swagata, Supriya Das, Anupam Roy, Uttam Pal, and Nakul C. Maiti. "Orientation of tyrosine side chain in neurotoxic Aβ differs in two different secondary structures of the peptide." Royal Society Open Science 3, no. 10 (October 2016): 160112. http://dx.doi.org/10.1098/rsos.160112.

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Amyloid β (Aβ) peptide is present as a major component in amyloid plaque that is one of the hallmarks of Alzheimer's disease. The peptide contains a single tyrosine residue and Aβ has a major implication in the pathology of the disease progression. Current investigation revealed that the tyrosine side chain attained two different critical stereo orientations in two dissimilar conformational states of the peptide. The extended α-helical structure of the peptide observed in an apolar solvent or methanol/water mixture became disordered in aqueous medium and the radius of gyration decreased. In aqueous medium, the torsional angle around C α –C β of tyrosine group became −60°. However, in its α-helical conformation in an apolar system, the measured angle was 180° and this rotameric state may be reasoned behind stronger tyrosine fluorescence compared with the disordered state of the peptide. Molecular dynamics simulation analyses and spectroscopic studies have helped us to understand the major structural changes in the secondary structure of the peptide in the two conformational states. A conformational clustering indicated that the compact state is more stable with tyrosine residue attaining the torsion angle value of −60°, whereas the native state (in HFIP/water mixture) is prevalent at a torsion angle value of −180°. High solvent accessibility has possibly stabilized the particular rotameric state (−60°) of the tyrosine residue and could be the reason behind decrease in fluorescence of the sole tyrosine residue in an aqueous buffer solution (pH 7.4) compared with its fluorescence in the α-helical structure in the micellar environment.

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31

Pratt, Cindy C., and Paul M. M. Weers. "Lipopolysaccharide binding of an exchangeable apolipoprotein, apolipophorin III, from Galleria mellonella." Biological Chemistry 385, no. 11 (November 1, 2004): 1113–19. http://dx.doi.org/10.1515/bc.2004.145.

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AbstractA new role of apolipophorin III (apoLp-III) as an immune activator has emerged recently. To gain insight into this novel function, the interaction of apoLp-III with lipopoly-saccharide (LPS) was investigated. ApoLp-III fromGalleria mellonellawas incubated with LPS fromEscherichia coliO55:B5, and analyzed by non-denaturing polyacrylamide gel electrophoresis (PAGE). Protein staining showed that apoLp-III mobility was significantly reduced. In addition, silver and LPS fluorescent staining demonstrated that LPS mobility was increased upon incubation with apoLp-III. This result suggests association of apoLp-III with LPS. Sodium dodecyl sulfate (SDS) PAGE analysis showed decreased apoLp-III mobility upon LPS addition, indicative of LPS apoLp-III interaction in the presence of SDS. The unique tyrosine residue that resides in apoLp-III was used to provide additional evidence for LPS binding interaction. In the absence of LPS, apoLp-III tyrosine fluorescence was relatively low. However, LPS addition resulted in a progressive increase in the fluorescence intensity, indicating tertiary rearrangement in the environment of tyrosine 142 upon LPS interaction. Other well-characterized apoLp-IIIs were also examined for LPS binding.Manduca sexta,Bombyx moriandLocusta migratoriaapoLp-III were all able to interact with LPS. The ability of apoLp-III to form complexes with LPS supports the proposed role of apoLp-III in innate immunity.

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32

Kovács, L., U. Hegde, S. Padhye, G. Bernát, and S. Demeter. "Effects of Potassium-(picrate)-(18-crown-6) on the Photosynthetic Electron Transport." Zeitschrift für Naturforschung C 51, no. 7-8 (August 1, 1996): 539–47. http://dx.doi.org/10.1515/znc-1996-7-813.

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Abstract The effects of potassium-(picrate)-(18-crown-6) on the electron transport of photosystem II was investigated in isolated pea thylakoids. Low concentrations of the compound inhibited the fast decay of fluorescence yield associated with electron transfer between the primary (QA) and secondary (QB) quinone electron acceptor and increased the intermediary level of fluorescence to the Fmax level. The decay half-time of fluorescence yield measured in the presence of DCMU(S2QA- charge recombination) decreased from about 1.8 s to about 0.3 s in thylakoids treated with potassium-(picrate)-(18-crown-6). While the inhibition of electron transport by DCMU gave rise to the appearance of a thermoluminescence band at about + 10°C (S2QA- charge recombination) addition of potassium-(picrate)-(18-crown-6) resulted in a thermoluminescence band at about -10°C. Increasing concentrations of potassium-(picrate)-(18-crown-6) diminished the fluorescence yield and the -10°C TL band and abolished the Signal IIS and Signal IIf EPR signals of the tyrosine-D and tyrosine-Z electron donors, respectively. The phenolic-type inhibitor, potassium picrate had the same effect on thermoluminescence and on the tyrosine EPR signals. It is concluded that potassium-(picrate)-(18-crown-6) is a phenolic type inhibitor owing to its picrate constituent. At low concentrations picrate and potassium-(picrate)-18-crown) not only block the electron transport between QA and QB but they probably decrease the midpoint redox potential of QA, as well. At high concentrations they also inhibit the light-induced oxidation of the tyrosine-D and tyrosine-Z donors.

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33

Erben, Antonija, Josipa Matić, Nikola Basarić, and Ivo Piantanida. "The Phenanthridine-modified Tyrosine Dipeptide." Croatica chemica acta 92, no. 2 (2019): 249–58. http://dx.doi.org/10.5562/cca3542.

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Dipeptide 4 containing two unnatural amino acids, a modified tyrosine and a phenanthridine derivative, was synthesized. Binding of the dipeptide to a series of polynucleotides including ct-DNA, poly A - poly U, poly (dAdT)2, poly dG - poly dC and poly (dGdC)2 was investigated by thermal denaturation experiments, fluorescence spectroscopy and circular dichroism. Thermal denaturation experiments indicated that dipeptide 4 at pH 5.0, when phenanthridine is protonated, stabilizes ds-DNA, whereas it destabilizes ds-RNA. At pH 7.0, when the phenanthridine is not protonated, effects of 4 to the polynucleotide melting temperatures are negligible. At pH 5.0, dipeptide 4 stabilized DNA double helices, and the changes in the CD spectra suggest different modes of binding to ds-DNA, most likely the intercalation to poly dG- poly dC and non-specific binding in grooves of other DNA polynucleotides. At variance to ds-DNA, addition of 4 destabilized ds-RNA against thermal denaturation and CD results suggest that addition of 4 probably induced dissociation of ds-RNA into ss-RNA strands due to preferred binding to ss-RNA. Thus, 4 is among very rare small molecules that stabilize ds-DNA but destabilize ds-RNA. However, fluorescence titrations with all polynucleotides at both pH values gave similar binding affinity (log Ka ≈ 5), indicating nonselective binding. Preliminary photochemical experiments suggest that dipeptide 4 reacts in the photochemical reaction, which affects polynucleotides chirality, presumably via quinone methide intermediates that alkylate DNA.

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34

McLaughlin, Stuart, Steven O. Smith, Michael J. Hayman, and Diana Murray. "An Electrostatic Engine Model for Autoinhibition and Activation of the Epidermal Growth Factor Receptor (EGFR/ErbB) Family." Journal of General Physiology 126, no. 1 (June 13, 2005): 41–53. http://dx.doi.org/10.1085/jgp.200509274.

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We propose a new mechanism to explain autoinhibition of the epidermal growth factor receptor (EGFR/ErbB) family of receptor tyrosine kinases based on a structural model that postulates both their juxtamembrane and protein tyrosine kinase domains bind electrostatically to acidic lipids in the plasma membrane, restricting access of the kinase domain to substrate tyrosines. Ligand-induced dimerization promotes partial trans autophosphorylation of ErbB1, leading to a rapid rise in intracellular [Ca2+] that can activate calmodulin. We postulate the Ca2+/calmodulin complex binds rapidly to residues 645–660 of the juxtamembrane domain, reversing its net charge from +8 to −8 and repelling it from the negatively charged inner leaflet of the membrane. The repulsion has two consequences: it releases electrostatically sequestered phosphatidylinositol 4,5-bisphosphate (PIP2), and it disengages the kinase domain from the membrane, allowing it to become fully active and phosphorylate an adjacent ErbB molecule or other substrate. We tested various aspects of the model by measuring ErbB juxtamembrane peptide binding to phospholipid vesicles using both a centrifugation assay and fluorescence correlation spectroscopy; analyzing the kinetics of interactions between ErbB peptides, membranes, and Ca2+/calmodulin using fluorescence stop flow; assessing ErbB1 activation in Cos1 cells; measuring fluorescence resonance energy transfer between ErbB peptides and PIP2; and making theoretical electrostatic calculations on atomic models of membranes and ErbB juxtamembrane and kinase domains.

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35

Hughes, Craig E., Alice Y. Pollitt, Jun Mori, Johannes A. Eble, Michael G. Tomlinson, John H. Hartwig, Christopher A. O'Callaghan, Klaus Fütterer, and Steve P. Watson. "CLEC-2 activates Syk through dimerization." Blood 115, no. 14 (April 8, 2010): 2947–55. http://dx.doi.org/10.1182/blood-2009-08-237834.

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Abstract The C-type lectin receptor CLEC-2 activates platelets through Src and Syk tyrosine kinases, leading to tyrosine phosphorylation of downstream adapter proteins and effector enzymes, including phospholipase-C γ2. Signaling is initiated through phosphorylation of a single conserved tyrosine located in a YxxL sequence in the CLEC-2 cytosolic tail. The signaling pathway used by CLEC-2 shares many similarities with that used by receptors that have 1 or more copies of an immunoreceptor tyrosine-based activation motif, defined by the sequence Yxx(L/I)x6-12Yxx(L/I), in their cytosolic tails or associated receptor chains. Phosphorylation of the conserved immunoreceptor tyrosine-based activation motif tyrosines promotes Syk binding and activation through binding of the Syk tandem SH2 domains. In this report, we present evidence using peptide pull-down studies, surface plasmon resonance, quantitative Western blotting, tryptophan fluorescence measurements, and competition experiments that Syk activation by CLEC-2 is mediated by the cross-linking through the tandem SH2 domains with a stoichiometry of 2:1. In support of this model, cross-linking and electron microscopy demonstrate that CLEC-2 is present as a dimer in resting platelets and converted to larger complexes on activation. This is a unique mode of activation of Syk by a single YxxL-containing receptor.

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36

Huang, Lei, Lianzhi Li, Haili Li, Chaohui Gao, Hui Cui, and Xiangshi Tan. "Multispectroscopic Study of the Interaction of Chloramphenicol with Human Neuroglobin." Spectroscopy: An International Journal 27 (2012): 143–54. http://dx.doi.org/10.1155/2012/192591.

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The interaction between chloramphenicol (CHL) and neuroglobin (Ngb) has been investigated by using fluorescence, synchronous fluorescence, UV-Vis and circular dichroism (CD) spectroscopy. It has been found that CHL molecule can quench the intrinsic fluorescence of Ngb in a way of dynamic quenching mechanism, which was supported by UV-Vis spectral data. Their effective quenching constants (KSV) are2.2×104,2.6×104,and 3.1×104 L⋅mol−1at 298 K, 303 K, and 308 K, respectively. The enthalpy change (ΔH) and entropy change (ΔS) for this reaction are 26.42 kJ⋅mol−1and 171.7 J⋅K−1, respectively. It means that the hydrophobic interaction is the main intermolecular force of the interaction between CHL and Ngb. Synchronous fluorescence spectra showed that the microenvironment of tryptophan and tyrosine residues of Ngb has been changed slightly. The fluorescence quenching efficiency of CHL to tyrosine residues is a little bit more than that to tryptophan residues of Ngb. Furthermore, CD spectra indicated that CHL can induce the formation of α-helix of Ngb.

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37

Donato, H., R. S. Mani, and C. M. Kay. "Spectral studies on the cadmium-ion-binding properties of bovine brain S-100b protein." Biochemical Journal 276, no. 1 (May 15, 1991): 13–18. http://dx.doi.org/10.1042/bj2760013.

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The effect of Cd2+ binding on bovine brain S-100b protein was studied using c.d. u.v. difference spectroscopy and fluorescence measurements. At pH 7.5, S-100b protein binds two Cd2+ ions per monomer with a Kd value of 3 x 10(-5) M. Addition of Cd2+ resulted in perturbing the single tyrosine residue (Tyr17) in the protein as indicated by u.v. difference spectroscopy and aromatic c.d. measurements. In the presence of Cd2+, the tyrosine residue moves to a more non-polar environment, since a red shift was observed in the u.v. difference spectrum. When the protein was excited at 278 nm, the tyrosine fluorescence emission maximum was centred at 306 nm. Cd2+ addition resulted in an increase in intrinsic fluorescence intensity. Fluorescence titration with Cd2+ indicated the protein binds Cd2+ with a Kd value of 3 x 10(-5) M. 2-p-Toluidinylnaphthalene-6-sulphonate-labelled protein, when excited at 345 nm, had a fluorescence emission maximum at 440 nm. Addition of Cd2+ to labelled protein resulted in a 5-fold increase in fluorescence intensity accompanied by a 5 nm blue shift in the emission maximum, suggesting that the probe, in the presence of Cd2+, moves to a hydrophobic domain. U.v. difference spectroscopic studies indicated a unique Cd2(+)-binding site on the protein, since Cd2+ addition yielded a large positive absorption band in the 240 nm region that is not found with either Ca2+ or Zn2- ions. Similar absorption bands have been observed in Cd-protein complexes such as Cd-metallothionein [Vasak, Kagi & Hill (1981) Biochemistry 20, 2852-2856] and also in model complexes of Cd2+ with 2-mercaptoethanol. This absorption band is believed to arise as a result of charge-transfer transitions between the thiolate and Cd2+. Of the two Cd2- -binding sites on the beta-chain, one must be located at the N-terminal end near the single tyrosine residue, since Cd2- and Zn2+ produced similar effects on the intrinsic protein fluorescence. The other Cd2+ site which is unique to Cd2+ must be Cys84, located at the C-terminal end.

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38

Zhdanova, Nadezda G., Evgeny A. Shirshin, Eugene G. Maksimov, Ivan M. Panchishin, Alexander M. Saletsky, and Victor V. Fadeev. "Tyrosine fluorescence probing of the surfactant-induced conformational changes of albumin." Photochemical & Photobiological Sciences 14, no. 5 (2015): 897–908. http://dx.doi.org/10.1039/c4pp00432a.

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39

Golub, Maksym, Virginia Guillon, Guillaume Gotthard, Dominik Zeller, Nicolas Martinez, Tilo Seydel, Michael M. Koza, et al. "Dynamics of a family of cyan fluorescent proteins probed by incoherent neutron scattering." Journal of The Royal Society Interface 16, no. 152 (March 2019): 20180848. http://dx.doi.org/10.1098/rsif.2018.0848.

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Cyan fluorescent proteins (CFPs) are variants of green fluorescent proteins in which the central tyrosine of the chromophore has been replaced by a tryptophan. The increased bulk of the chromophore within a compact protein and the change in the positioning of atoms capable of hydrogen bonding have made it difficult to optimize their fluorescence properties, which took approximately 15 years between the availability of the first useable CFP, enhanced cyan fluorescent protein (ECFP), and that of a variant with almost perfect fluorescence efficiency, mTurquoise2. To understand the molecular bases of the progressive improvement in between these two CFPs, we have studied by incoherent neutron scattering the dynamics of five different variants exhibiting progressively increased fluorescence efficiency along the evolution pathway. Our results correlate well with the analysis of the previously determined X-ray crystallographic structures, which show an increase in flexibility between ECFP and the second variant, Cerulean, which is then hindered in the three later variants, SCFP3A (Super Cyan Fluorescent Protein 3A), mTurquoise and mTurquoise2. This confirms that increasing the rigidity of the direct environment of the fluorescent chromophore is not the sole parameter leading to brighter fluorescent proteins and that increased flexibility in some cases may be helpful.

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40

Zhang, Sheng, Lan Chen, Sanjai Kumar, Li Wu, David S. Lawrence, and Zhong-Yin Zhang. "An affinity-based fluorescence polarization assay for protein tyrosine phosphatases." Methods 42, no. 3 (July 2007): 261–67. http://dx.doi.org/10.1016/j.ymeth.2007.02.008.

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41

Wiczk, Wiesław, Alicja Rzeska, Joanna Łukomska, Krystyna Stachowiak, Jerzy Karolczak, Joanna Malicka, and Leszek Łankiewicz. "Mechanism of fluorescence quenching of tyrosine derivatives by amide group." Chemical Physics Letters 341, no. 1-2 (June 2001): 99–106. http://dx.doi.org/10.1016/s0009-2614(01)00470-5.

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42

Wouters, Fred S., and Philippe I. H. Bastiaens. "Fluorescence lifetime imaging of receptor tyrosine kinase activity in cells." Current Biology 9, no. 19 (October 1999): 1127—S1. http://dx.doi.org/10.1016/s0960-9822(99)80484-9.

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43

Tan, Liang, Shouzhuo Yao, Qingji Xie, and Youyu Zhang. "Studies on Interaction of Tyrosine with DNA by Fluorescence Spectra." Analytical Letters 36, no. 10 (January 9, 2003): 2167–81. http://dx.doi.org/10.1081/al-120023709.

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44

Nordlund, T. M., X. Y. Liu, and J. H. Sommer. "Fluorescence polarization decay of tyrosine in lima bean trypsin inhibitor." Proceedings of the National Academy of Sciences 83, no. 23 (December 1, 1986): 8977–81. http://dx.doi.org/10.1073/pnas.83.23.8977.

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45

Choi, Kihang, Bongjeong Park, So-Yeong Han, and Hee Choon Ahn. "Fluorescence Probes for Tyrosine Dephosphorylation Based on Coumarin–Proline Conjugates." Chemistry Letters 40, no. 3 (March 5, 2011): 290–91. http://dx.doi.org/10.1246/cl.2011.290.

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46

Seidel, Claus, Andreas Orth, and Karl-Otto Greulich. "ELECTRONIC EFFECTS ON THE FLUORESCENCE OF TYROSINE IN SMALL PEPTIDES." Photochemistry and Photobiology 58, no. 2 (August 1993): 178–84. http://dx.doi.org/10.1111/j.1751-1097.1993.tb09546.x.

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47

Lakowicz, Joseph R., Borys Kierdaszuk, Patrik Callis, Henryk Malak, and Ignacy Gryczynski. "Fluorescence anisotropy of tyrosine using one-and two-photon excitation." Biophysical Chemistry 56, no. 3 (November 1995): 263–71. http://dx.doi.org/10.1016/0301-4622(95)00040-5.

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48

Fernández-Belda, Francisco, JoséA Teruel, and Juan C. Gómez-Fernández. "Structural studies of mitochondrial coupling factor 1 using tyrosine fluorescence." International Journal of Biochemistry 17, no. 2 (January 1985): 223–28. http://dx.doi.org/10.1016/0020-711x(85)90118-1.

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49

Seethala, Ramakrishna, and Rolf Menzel. "A Homogeneous, Fluorescence Polarization Assay for Src-Family Tyrosine Kinases." Analytical Biochemistry 253, no. 2 (November 1997): 210–18. http://dx.doi.org/10.1006/abio.1997.2365.

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50

Budkevich, Roman O., Anastasia I. Eremina, Ivan A. Evdokimov, Nikita M. Fedortsov, Alexey A. Martak, and Elena V. Budkevich. "THE PHYSICAL PROPERTIES OF THE CASEIN IN SOLUTION: EFFECT OF ULTRA-HIGH PRESSURE." Food systems 1, no. 3 (October 11, 2018): 4–12. http://dx.doi.org/10.21323/2618-9771-2018-1-3-4-12.

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The aim of this work was to study the effect of pressure (50; 90; 160; 250; 350 MPa) on a physical property of casein micelle: hydrodynamic radius, tyrosine and tryptophan fluorescence and IR spectra characteristics. According to photon-correlation spectroscopy, the average hydrodynamic radius of the casein micelle was 128 nm, increasing at 50 MPa to 467 nm with the formation of conglomerates. Further increase of pressure led to the formation of two fractions of particles, differing in hydrodynamic radius. At a pressure of 350 MPa, an average radius of 75 % of particles was 121 nm. Comparison of hydrodynamic radius and tyrosine fluorescence revealed a decrease in the intensity of the glow with an increase in the proportion of large particles and an increase in the radiation in the solution with a decrease of the micelles size. The increase of casein fluorescence by tryptophan and its decrease by tyrosine indicate a change in the conformation of protein molecules during pressure treatment. FTIR spectroscopy revealed a change in the intensity of the optical density in the range of amide I, amide II and valence bonds of tyrosine, confirming the absence of new bonds. The obtained physical data indicate a change in the structure of casein micelles with an increase in the proportion (25 %) of large particles after the action of high pressure (350mpa), which should be taken into account in milk processing. The fluorescence of casein during pressure treatment is a poorly investigated physical indicator and can be important for the processing of raw milk.

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