摘要:

A cyclic tetradepsipeptide with a sequence corresponding to AM‐toxin III (a phytotoxic peptide) was synthesized by a conventional method in order to confirm the proposed structure. This was mediated through a deamination reaction of precursor cyclotetradepsipeptide containing ad‐2, 3‐diaminopropionic acid residue by the Hofmann degradation method. The synthetic peptide and natural AM‐toxin III were identical in regard to t.l.c., crystal form, mass spectrum and biological activity in causing necrosis on apple leaves. Two analogs, [1‐O‐methyl‐l‐tyrosine]‐AM‐toxin and [1‐l‐tyrosine]‐AM‐toxin, were synthesized simultaneously. [1‐l‐Tyrosine]‐AM‐toxin showed extremely weak activity; the relationship between the bulkiness of an aromatic side chain at position 1 of AM‐toxin III and

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1982.tb03026.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Formation of pyrrolidone carboxylic acid (pyroglutamic acid) residues from amino‐terminal glutaminyl residues in peptides was shown to be catalyzed by weak acids, but not by strong acids. During dicyclohexylcarbodiimide‐mediated coupling reactions theNα‐protected amino acid reagent accelerated this cyclization and resulted in a significant amount of chain termination. The side reaction could be minimized by accelerating the coupling reaction and simultaneously reducing the time of exposure to weak acids. The most effective procedure was to couple in dimethylformamide with the preformed symmetric anhydride of the amin

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1982.tb03027.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Linear proline‐containing peptides H‐Gly‐(Pro)n‐OH with n = 2–5 have been investigated by measuring the circular dichroism in water as a function of pH, temperature and salt added. By comparison with similar studies conducted by others on oligoprolines it has been possible to demonstrate the formation of a helical (polyproline II‐like) structure at the

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1982.tb03028.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1982.tb03029.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY