✦ LIBER ✦

Synthesis and conformation of the 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: 779 KB
Volume: 22
Category: Article
ISSN: 0006-3525
DOI: 10.1002/bip.360221006

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✦ Synopsis

Cyclic octapeptides, cyclo(X-Pro)4, where X represents Phe, Leu, or Lys(Z), were synthesized and their conformations investigated. A Cz-symmetric conformer containing two cis peptide bonds was found in all of these cyclic octapeptides. The numbers of available conformations due to the cis-trans isomerization of Pro peptide bonds depended on the nature of the solvent and X residue: they decreased in the following order: cyclo[Lys(Z)-Pro]~ > cycl~(Leu-Pro)~ > cyclo(Phe-Pro)4 in CDCla. 13C spin-lattice relaxation times ( 2 ' 1 ) of these cyclic octapeptides were measured, and the contribution of segmental mobility to 2 ' 1 was found t o vary with the nature of the X residue.

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