Theoretical study on formation of thioesters via O-to-S acyl transfer |
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Authors: | Chen Wang Qing-Xiang Guo |
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Institution: | 1. College of Chemistry & Chemical Engineering, Shaoxing University, Shaoxing, 312000, China 2. Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China
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Abstract: | Peptide thioester preparation via intramolecular O-to-S acyl transfer is a recently developed method for protein chemical synthesis through Fmoc chemistry. Theoretical calculations have been carried out to study the mechanism for the formation of thioesters via O-to-S acyl transfer. It is found that the O-to-S acyl transfer occurs via an anionic stepwise mechanism in which the cleavage of the C-O bond is the rate-limiting step. The side reaction of hydrolysis also proceeds through an anionic stepwise process, and its rate-limiting step is the attack of the hydroxide ion on the carbonyl carbon. Increase of the chain length between the ester O atom and the S atom can increase the energy barrier of the O-to-S acyl transfer. On the other hand, substituents at the ??-position of the ester can reduce the energy barrier. |
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Keywords: | density functional theory native chemical ligation thioester O-to-S acyl transfer hydrolysis |
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