N-Methylimidazolium chloride-catalyzed pyrophosphate formation: Application to the synthesis of Lipid I and NDP-sugar donors
摘要:
N-Methylimidazolium chloride is found to catalyze a coupling reaction between monophosphates and activated phosphorous-nitrogen intermediates such as a phosphorimidazolide and phosphoromorpholidate to form biologically important unsymmetrical pyrophosphate diesters. The catalyst is much more active, cheaper, and less explosive than 1H-tetrazole, known as the best catalyst for the pyrophosphate formation over a decade. The mild and neutral reaction conditions are compatible with allylic pyrophosphate formation in Lipid I syntheisis. (31)P NMR experiments suggest that the catalyst acts not only as an acid but also as a nucleophile to form cationic and electrophilic phosphor-N-methylimidazolide intermediates in the pyrophosphate formation. (c) 2011 Elsevier Ltd. All rights reserved.
Synthesis of a Comprehensive Polyprenol Library for the Evaluation of Bacterial Enzyme Lipid Substrate Specificity
作者:Baolin Wu、Robert Woodward、Liuqing Wen、Xuan Wang、Guohui Zhao、Peng George Wang
DOI:10.1002/ejoc.201301089
日期:2013.12
Polyprenols, a type of universal glycan lipid carrier, play important roles for glycan bio-assembly in wide variety of living systems. Chemical synthesis of natural polyisoprenols such as undecaprenol and dolichols, but especially their homologs, could serves as a powerful molecular tool to dissect and define the functions of enzymes involved in glycan biosynthesis. In this paper, we report an efficient
Synthesis of Heptaprenyl−Lipid IV to Analyze Peptidoglycan Glycosyltransferases
作者:Yi Zhang、Eric J. Fechter、Tsung-Shing Andrew Wang、Dianah Barrett、Suzanne Walker、Daniel E. Kahne
DOI:10.1021/ja069060g
日期:2007.3.1
tremendous potential as antibiotic targets, but the potential has not yet been realized. Mechanistic studies have been hampered by a lack of substrates to monitor enzymatic activity. We report here the totalsynthesis of heptaprenyl−Lipid IV and its use to study two different PGTs from E. coli. We show that one PGT can couple Lipid IV to itself whereas the other can only couple Lipid IV to Lipid II. These
细菌被包含肽聚糖层的细胞壁包围,肽聚糖的完整性对于细菌的生存至关重要。在肽聚糖生物合成的最后阶段,肽聚糖糖基转移酶 (PGTs;也称为转糖基酶) 催化脂质 II 聚合形成线性聚糖链。PGTs 作为抗生素靶点具有巨大的潜力,但其潜力尚未实现。由于缺乏监测酶活性的底物,机制研究受到阻碍。我们在此报告了庚烯基-脂质 IV 的全合成及其用于研究来自大肠杆菌的两种不同 PGT。我们表明一个 PGT 可以将脂质 IV 与其自身结合,而另一个只能将脂质 IV 与脂质 II 结合。
Transpeptidase-Mediated Incorporation of <scp>d</scp>-Amino Acids into Bacterial Peptidoglycan
作者:Tania J. Lupoli、Hirokazu Tsukamoto、Emma H. Doud、Tsung-Shing Andrew Wang、Suzanne Walker、Daniel Kahne
DOI:10.1021/ja2040656
日期:2011.7.20
The beta-lactams are the most important class of antibiotics in clinical use. Their lethal targets are the transpeptidase domains of penicillin binding proteins (PBPs), which catalyze the cross-linking of bacterial peptidoglycan (PG) during cell wall synthesis. The transpeptidation reaction occurs in two steps, the first being formation of a covalent enzyme intermediate and the second involving attack of an amine on this intermediate. Here we use defined PG substrates to dissect the individual steps catalyzed by a purified E. coli transpeptidase. We demonstrate that this transpeptidase accepts a set of structurally diverse D-amino acid substrates and incorporates them into PG fragments. These results provide new information on donor and acceptor requirements as well as a mechanistic basis for previous observations that noncanonical D-amino acids can be introduced into the bacterial cell wall.