Crystal structures of heterochiral peptides .2. tert-Boc-valyl-D-alanyl-leucyl-alanyl methoxide

Abstract

Crystal structure of a heterochiral peptide, viz. Bac-Val(1)-D-Ala(2)-Leu(3)-Ala(4)-OMe with a D chiral residue in the second position of a sequence, has been determined [a = 40.44(1), b = 4.887(5), c = 15.381(5) Angstrom, beta = 109.6(1)degrees, space group C2, Z = 4, R = 0.11]. The peptide is in a parallel beta-sheet structure terminated by a distinct local bend. The structure is stabilised by N-H ... O as well as C-alpha-N ... O hydrogen bonds,The contiguous C-alpha-H ... O hydrogen bond observed in this structure is an unique observation. (C) Munksgaard 1997