Grant-in-Aid for Scientific Research (C)

点击翻译按钮获取中文摘要

To investigare the formation mechanism of gramicidin S (GS) by the dimerization-cyclization of pentapeptide active eaters having no protecting group on the side chain of the Orn residue, the cyclization of four H-X-Pro-Y-Orn-Leu-ONSu's (X=L- or D-Phe, Y=L- or D-Val, -ONSu=succinimide ester) was examined. Only H-D-Phe-Pro-Val-Orn-Leu-ONSu gave semi-GS (cyclic monomer) and GS (cyclic dimer).1. H-D-Phe-Pro-Val-Orn-Leu-ONSu2. H-Phe-Pro-D-Val-Orn-Leu-ONSu3. H-Phe-Pro-Val-Orn-Leu-ONSu4. H-D-Phe-Pro-D-Val-Orn-Leu-ONSuThe active ester with D-Phe-Pro-D-Val sequence produced exclusively [D-Val] -semi-GS in 58% yield. On the other hand, the active esters having Phe-Pro-Val and Phe-Pro-D-Val sequences did not yield any amount of cyclic monomer and cyclic dimer. A good correlation among the CD spectra in ethanol, NMR spectra in DMSO-d_6 of the pentapeptide ethyl esters, and the cyclization of the active esters was found.