Relevant bibliographies by topics / Carboxyl and acyl transfer reactions

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Academic literature on the topic 'Carboxyl and acyl transfer reactions'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Carboxyl and acyl transfer reactions"

1

Bérces, Attila, Dennis M. Whitfield, Tomoo Nukada, Iwona do Santos Z., Agnes Obuchowska, and Jiri J. Krepinsky. "Is acyl migration to the aglycon avoidable in 2-acyl assisted glycosylation reactions?" Canadian Journal of Chemistry 82, no. 7 (2004): 1157–71. http://dx.doi.org/10.1139/v04-059.

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This report unequivocally separates orthoester formation from acyl transfer for the first time and indicates possible routes to eliminate 2-O-acyl transfer during glycosylation reactions. Experimental evidence is shown that acyl transfer from 2-O-acyl-3,4,6-tri-O-benzyl-D-galactopyranose-derived glycosyl donors decreases in the order formyl > acetyl > pivaloyl. The 2-O-benzoyl derivatives are more variable, in some cases transferring easily, and in others not at all. Density functional theory (DFT) calculations of the structure and energetics of dioxolenium ion and related intermediates suggest that a proton transfer pathway from the nucleophile to O-2 provides an explanation for the observed trends. These DFT calculations of the proton transfer pathway support a mechanism in which a relay molecule is involved. Further DFT calculations used a constraint based on linear combinations of six bond lengths to establish the sequence of bond breaking and bond forming. The calculated anomeric carbon to former carbonyl oxygen bond that breaks during acyl transfer is the longest in the formyl case and shortest in those that exhibit little or no acyl transfer. Rotation about the aromatic to carbonyl Ph—C(=O) bond is different from the alkyl series. Analysis of this proposed TS led to the postulate that 2,6-substitution may hinder rotation even more. Thus, the 2,6-dimethylbenzoyl analogue was synthesized and it does not transfer directly or by rearrangement of its readily formed orthoester. DFT calculations suggested that 2,6-dimethoxybenzoyl should also not transfer easily. Experimentally, this proved to be the case and this new 2-O-acyl protecting group cleaves at 50 °C with a 1 mol/L solution of LiOH in methanol. Thus, a calculated transition state has led to a prototype of a protecting group that solves a major problem in oligosaccharide synthesis.Key words: glycosylation, carbohydrates, quantum chemistry, reaction mechanism, neighboring-group effects.
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2

Nguyen-Distèche, M., M. Leyh-Bouille, S. Pirlot, J. M. Frère, and J. M. Ghuysen. "Streptomyces K15 dd-peptidase-catalysed reactions with ester and amide carbonyl donors." Biochemical Journal 235, no. 1 (1986): 167–76. http://dx.doi.org/10.1042/bj2350167.

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In water, the purified 26 000-Mr membrane-bound DD-peptidase of Streptomyces K15 hydrolyses the ester carbonyl donor Ac2-L-Lys-D-Ala-D-lactate (release of D-lactate) and the amide carbonyl donor Ac2-L-Lys-D-Ala-D-Ala (release of D-alanine) with accumulation of acyl- (Ac2-L-Lys-D-alanyl-)enzyme. Whereas hydrolysis of the ester substrate proceeds to completion, hydrolysis of the amide substrate is negligible because of the capacity of the K15 DD-peptidase for utilizing the released D-alanine in a transfer reaction (Ac2-L-Lys-D-Ala-D-Ala + D-Ala→Ac2-L-Lys-D-Ala-D-Ala + D-Ala) that maintains the concentration of the amide substrate at a constant level. In the presence of an amino acceptor X-NH2 (Gly-Gly or Gly-L-Ala) related to the Streptomyces peptidoglycan, both amide and ester carbonyl donors are processed without detectable accumulation of acyl-enzyme. Under proper conditions, the acceptor activity of water and, in the case of the amide substrate, the acceptor activity of the released D-alanine can be totally overcome so that the two substrates are quantitatively converted into transpeptidated product Ac2-L-Lys-D-Ala-NH-X (and hydrolysis is prevented). Experimental evidence suggests that the amino acceptor modifies both the binding of the carbonyl donor to the enzyme and the ensuing rate of enzyme acylation.
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3

Portada, Tomislav, Davor Margetić, and Vjekoslav Štrukil. "Mechanochemical Catalytic Transfer Hydrogenation of Aromatic Nitro Derivatives." Molecules 23, no. 12 (2018): 3163. http://dx.doi.org/10.3390/molecules23123163.

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Mechanochemical ball milling catalytic transfer hydrogenation (CTH) of aromatic nitro compounds using readily available and cheap ammonium formate as the hydrogen source is demonstrated as a simple, facile and clean approach for the synthesis of substituted anilines and selected pharmaceutically relevant compounds. The scope of mechanochemical CTH is broad, as the reduction conditions tolerate various functionalities, for example nitro, amino, hydroxy, carbonyl, amide, urea, amino acid and heterocyclic. The presented methodology was also successfully integrated with other types of chemical reactions previously carried out mechanochemically, such as amide bond formation by coupling amines with acyl chlorides or anhydrides and click-type coupling reactions between amines and iso(thio)cyanates. In this way, we showed that active pharmaceutical ingredients Procainamide and Paracetamol could be synthesized from the respective nitro-precursors on milligram and gram scale in excellent isolated yields.
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4

Yang, Haoyang, Biao Zhang, Wentao Zhong, Zhisheng Fu, and Zhiqiang Fan. "Modification of the Acyl Chloride Quench-Labeling Method for Counting Active Sites in Catalytic Olefin Polymerization." Catalysts 11, no. 6 (2021): 683. http://dx.doi.org/10.3390/catal11060683.

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The reliable and efficient counting of active sites in catalytic olefin polymerization has been realized by using acyl chloride as the quench-labeling agent. However, the molar ratio of acyl chloride to the alkylaluminum cocatalyst must be larger than 1 in order to completely depress side reactions between the quencher and Al-polymeryl that is formed via chain transfer reaction. In this work, a tetrahydrofuran/thiophene-2-carbonyl chloride (THF/TPCC) mixture was used as the quenching agent when counting the active sites of propylene polymerization catalyzed by MgCl2/Di/TiCl4 (Di = internal electron donor)-type Ziegler–Natta catalyst activated with triethylaluminum (TEA). When the THF/TEA molar ratio was 1 and the TPCC/TEA molar ratio was smaller than 1, the [S]/[Ti] ratio of the polymer quenched with the THF/TPCC mixture was the same as that quenched with only TPCC at TPCC/TEA > 1, indicating quench-labeling of all active sites bearing a propagation chain. The replacement of a part of the TPCC with THF did not influence the precision of active site counting by the acyl chloride quench-labeling method, but it effectively reduced the amount of acyl chloride. This modification to the acyl chloride quench-labeling method significantly reduced the amount of precious acyl chloride quencher and brought the benefit of simplifying polymer purification procedures after the quenching step.
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5

Grandchamps, J., M. Nguyen-Distèche, C. Damblon, J. M. Frère, and J. M. Ghuysen. "Streptomyces K15 active-site serine dd-transpeptidase: specificity profile for peptide, thiol ester and ester carbonyl donors and pathways of the transfer reactions." Biochemical Journal 307, no. 2 (1995): 335–39. http://dx.doi.org/10.1042/bj3070335.

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The Streptomyces K15 transferase is a penicillin-binding protein presumed to be involved in bacterial wall peptidoglycan crosslinking. It catalyses cleavage of the peptide, thiol ester or ester bond of carbonyl donors Z-R1-CONH-CHR2-COX-CHR3-COO- (where X is NH, S or O) and transfers the electrophilic group Z-R1-CONH-CHR2-CO to amino acceptors via an acyl-enzyme intermediate. Kinetic data suggest that the amino acceptor behaves as a simple alternative nucleophile at the level of the acyl-enzyme in the case of thiol ester and ester donors, and that it binds to the enzyme.carbonyl donor Michaelis complex and influences the rate of enzyme acylation by the carbonyl donor in the case of amide donors. Depending on the nature of the scissile bond, the enzyme has different requirements for substituents at positions R1, R2 and R3.
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6

Dasgupta, Sayani, Sharmishtha Samantaray, Dinkar Sahal, and Rajendra P. Roy. "Isopeptide Ligation Catalyzed by Quintessential Sortase A." Journal of Biological Chemistry 286, no. 27 (2011): 23996–4006. http://dx.doi.org/10.1074/jbc.m111.247650.

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The housekeeping transpeptidase sortase A (SrtA) from Staphyloccocus aureus catalyzes the covalent anchoring of surface proteins to the cell wall by linking the threonyl carboxylate of the LPXTG recognition motif to the amino group of the pentaglycine cross-bridge of the peptidoglycan. SrtA-catalyzed ligation of an LPXTG containing polypeptide with an aminoglycine-terminated moiety occurs efficiently in vitro and has inspired the use of this enzyme as a synthetic tool in biological chemistry. Here we demonstrate the propensity of SrtA to catalyze “isopeptide” ligation. Using model peptide sequences, we show that SrtA can transfer LPXTG peptide substrates to the ϵ-amine of specific Lys residues and form cyclized and/or a gamut of branched oligomers. Our results provide insights about principles governing isopeptide ligation reactions catalyzed by SrtA and suggest that although cyclization is guided by distance relationship between Lys (ϵ-amine) and Thr (α-carboxyl) residues, facile branched oligomerization requires the presence of a stable and long-lived acyl-enzyme intermediate.
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7

Viswambharan, Baby, Tatsuya Okimura, Satoko Suzuki, and Sentaro Okamoto. "Synthesis and Catalytic Properties of 4-Aryl-2,3-dihydro-4H-pyrimido[2,3-b]benzothiazoles for Asymmetric Acyl or Carboxyl Group Transfer Reactions." Journal of Organic Chemistry 76, no. 16 (2011): 6678–85. http://dx.doi.org/10.1021/jo200984n.

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8

Buckel, Wolfgang, Berta M. Martins, Albrecht Messerschmidt, and Bernard T. Golding. "Radical-mediated dehydration reactions in anaerobic bacteria." Biological Chemistry 386, no. 10 (2005): 951–59. http://dx.doi.org/10.1515/bc.2005.111.

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AbstractMost dehydratases catalyse the elimination of water from β-hydroxy ketones, β-hydroxy carboxylic acids or β-hydroxyacyl-CoA. The electron-withdrawing carbonyl functionalities acidify the α-hydrogens to enable their removal by basic amino acid side chains. Anaerobic bacteria, however, ferment amino acids via α- or γ-hydroxyacyl-CoA, dehydrations of which involve the abstraction of a β-hydrogen, which is ostensibly non-acidic (pKca. 40). Evidence is accumulating that β-hydrogens are acidified via transient conversion of the CoA derivatives to enoxy radicals by one-electron transfers, which decrease the pKto 14. The dehydrations of (R)-2-hydroxyacyl-CoA to (E)-2-enoyl-CoA are catalysed by heterodimeric [4Fe-4S]-containing dehydratases, which require reductive activation by an ATP-dependent one-electron transfer mediated by a homodimeric protein with a [4Fe-4S] cluster between the two subunits. The electron is further transferred to the substrate, yielding a ketyl radical anion, which expels the hydroxyl group and forms an enoxy radical. The dehydration of 4-hydroxybutyryl-CoA to crotonyl-CoA involves a similar mechanism, in which the ketyl radical anion is generated by one-electron oxidation. The structure of the FAD- and [4Fe-4S]-containing homotetrameric dehydratase is related to that of acyl-CoA dehydrogenases, suggesting a radical-based mechanism for both flavoproteins.
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9

Ghuysen, J. M., J. M. Frère, M. Leyh-Bouille, M. Nguyen-Distèche, and J. Coyette. "Active-site-serine d-alanyl-d-alanine-cleaving-peptidase-catalysed acyl-transfer reactions. Procedures for studying the penicillin-binding proteins of bacterial plasma membranes." Biochemical Journal 235, no. 1 (1986): 159–65. http://dx.doi.org/10.1042/bj2350159.

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Under certain conditions, the values of the parameters that govern the interactions between the active-site-serine D-alanyl-D-alanine-cleaving peptidases and both carbonyl-donor substrates and beta-lactam suicide substrates can be determined on the basis of the amounts of (serine ester-linked) acyl-protein formed during the reactions. Expressing the ‘affinity’ of a beta-lactam compound for a DD-peptidase in terms of second-order rate constant of enzyme acylation and first-order rate constant of acyl-enzyme breakdown rests upon specific features of the interaction (at a given temperature) and permits study of structure-activity relationships, analysis of the mechanism of intrinsic resistance and use of a ‘specificity index’ to define the capacity of a beta-lactam compound of discriminating between various sensitive enzymes. From knowledge of the first-order rate constant of acyl-enzyme breakdown and the given time of incubation, the beta-lactam compound concentrations that are necessary to achieve given extents of DD-peptidase inactivation can be converted into the second-order rate constant of enzyme acylation. The principles thus developed can be applied to the study of the multiple penicillin-binding proteins that occur in the plasma membranes of bacteria.
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10

Viswambharan, Baby, Tatsuya Okimura, Satoko Suzuki, and Sentaro Okamoto. "ChemInform Abstract: Synthesis and Catalytic Properties of 4-Aryl-2,3-dihydro-4H-pyrimido[2,3-b]benzothiazoles for Asymmetric Acyl or Carboxyl Group Transfer Reactions." ChemInform 42, no. 50 (2011): no. http://dx.doi.org/10.1002/chin.201150146.

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