Introduction The availability of site-specifically modified peptides is of vital importance for biochemical and biophysical studies. Biological methods, such as expression using bacteria, are useful. They are, howeve...Introduction The availability of site-specifically modified peptides is of vital importance for biochemical and biophysical studies. Biological methods, such as expression using bacteria, are useful. They are, however, not always applicable to the synthesis of peptides with sitespecific modifications. Chemical methods can be viable alternatives to those biological approaches. Peptides obtained by chemical and biological means,展开更多
Thioester method was improved by using Pac (phenacyl group) ester as protecting group of 3-mercaptopropionic acid. Two cyclopentapeptides c(Ala-Tyr-Leu-Ala-Gly) and c(Pro-Tyr-Leu- Ala-Gly) were synthesized successful...Thioester method was improved by using Pac (phenacyl group) ester as protecting group of 3-mercaptopropionic acid. Two cyclopentapeptides c(Ala-Tyr-Leu-Ala-Gly) and c(Pro-Tyr-Leu- Ala-Gly) were synthesized successfully by this method.展开更多
Thioester method for the synthesis of cyclopeptides is improved by using Pac (Pac = phenacyl, CH2COC6H5) ester as a protecting group of 3-mercaptopropionic acid. The Pac group is easy to be removed from C-terminal wit...Thioester method for the synthesis of cyclopeptides is improved by using Pac (Pac = phenacyl, CH2COC6H5) ester as a protecting group of 3-mercaptopropionic acid. The Pac group is easy to be removed from C-terminal with zinc in acetic acid. The protected glycine thioester and peptide thioesters synthesized by the unproved method, are easy to be purified, so the final linear peptides are pure enough for the following cyclization. Furthermore, this method is flexible for peptide chain elongation, either from C-terminal or from N-terminal. So it is an efficient and practical method for synthesis of bioactive peptides. Two N-protected pentapeptide thioesters, Boc-Pro-Tyr-Leu-Ala-GlySCH2CH2COOPac and Boc-Ala-Tyr-Leu-Ala-Gly-SCH2CH2-COOPac were synthesized by the improved thioester method. After deprotecting Pac ester with zinc in aqueous acetic acid and Boc group with trifluoroacetic acid in CH2C12, two free pentapeptide thioesters were obtained. Ag+ -assisted cyclization in acetate buffered solution afforded two cyclic pentapeptides c(Pro-Tyr-Leu-Ala-Gly) and c(Ala-Tyr-Leu-Ala-Gly). Effects of different buffer pH, different Ag+ concentrations, etc. on the cyclization were studied.展开更多
文摘Introduction The availability of site-specifically modified peptides is of vital importance for biochemical and biophysical studies. Biological methods, such as expression using bacteria, are useful. They are, however, not always applicable to the synthesis of peptides with sitespecific modifications. Chemical methods can be viable alternatives to those biological approaches. Peptides obtained by chemical and biological means,
文摘Thioester method was improved by using Pac (phenacyl group) ester as protecting group of 3-mercaptopropionic acid. Two cyclopentapeptides c(Ala-Tyr-Leu-Ala-Gly) and c(Pro-Tyr-Leu- Ala-Gly) were synthesized successfully by this method.
基金Project supported by the National Natural Science Foundation of China(No.29772001).
文摘Thioester method for the synthesis of cyclopeptides is improved by using Pac (Pac = phenacyl, CH2COC6H5) ester as a protecting group of 3-mercaptopropionic acid. The Pac group is easy to be removed from C-terminal with zinc in acetic acid. The protected glycine thioester and peptide thioesters synthesized by the unproved method, are easy to be purified, so the final linear peptides are pure enough for the following cyclization. Furthermore, this method is flexible for peptide chain elongation, either from C-terminal or from N-terminal. So it is an efficient and practical method for synthesis of bioactive peptides. Two N-protected pentapeptide thioesters, Boc-Pro-Tyr-Leu-Ala-GlySCH2CH2COOPac and Boc-Ala-Tyr-Leu-Ala-Gly-SCH2CH2-COOPac were synthesized by the improved thioester method. After deprotecting Pac ester with zinc in aqueous acetic acid and Boc group with trifluoroacetic acid in CH2C12, two free pentapeptide thioesters were obtained. Ag+ -assisted cyclization in acetate buffered solution afforded two cyclic pentapeptides c(Pro-Tyr-Leu-Ala-Gly) and c(Ala-Tyr-Leu-Ala-Gly). Effects of different buffer pH, different Ag+ concentrations, etc. on the cyclization were studied.
