✦ LIBER ✦

Complex formation with alkali and alkaline earth metal ions of cyclic octapeptides, cyclo(Phe-Pro)4, cyclo(Leu-Pro)4, and cyclo[Lys(Z)-Pro]4

✍ Scribed by Shunsaku Kimura; Yukio Imanishi

Publisher: Wiley (John Wiley & Sons)
Year: 1983
Tongue: English
Weight: 609 KB
Volume: 22
Category: Article
ISSN: 0006-3525
DOI: 10.1002/bip.360221106

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✦ Synopsis

Complex formation with alkali and alkaline earth metal ions of cycIic octapeptides, cyclo(Phe-Pro)c, cyclo(Leu-Pro)4, and cyclo[Lys(Z)-Pro]4 was investigated in relation to conformation. In an alcohol solution, cyclo(Phe-Pro)4 did not form complexes. However, cyclo(Leu-Pro)4 and cyclo[Lys(Z)-Pro]4 formed complexes selectively with Ba2+ and Ca2+ ions. Changing the solvent from alcohol to acetonitrile, the complexation behavior was very different. In acetonitrile, c~clo(Phe-Pro)~ was found to form a complex with Ba2+, and CD spectra of cyclo(Leu-Pro)4 and cyclo[Lys(Z)-Pro]4 changed sharply on complexation with K+. Rate constants of the complex formation between the cyclic octapeptides and metal salts were in the range of 0.7-12 L mol-1 min-' in an alcohol solution. One of the two types of complex formation in acetonitrile was much faster than that in an alcohol solution.

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