Crystal structure and conformational analyses of a synthetic tetrapeptide t-Boc-L-Val-Aib-Gly-L-Leu-OMe

Crystal structure of a terminally blocked synthetic peptide, t-Boc-L-Val-Aib-Gly-L-Leu-OMe has been investigated. Two different conformers of peptide with one co-crystallized water molecule, coexist in the crystal structure, in C2 space group. Both the conformers are stabilized by two intramolecular 1← 4 hydrogen bonds, between (Boc) C=O … HN (Gly) and (Val) C=O … HN (Leu), forming consecutive type II-I' β-turns. In the crystal, water interlinks peptide molecules, making a triangular bridge of pyramidal type. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)