CONFORMATIONAL STUDIES OF RETRO-INVERSO PEPTIDES - THE CRYSTAL AND MOLECULAR-STRUCTURE OF THE HYDANTOIN FROM H-ALA-G-ALA-MGLY-OBZL

The crystal structure of the hydantoin 1-[(S)-1'-animoethylmalonyl benzyl ester]-(S)-4-methylimidazolidin-2,5-dione (1) derived from the peptide H-ala-gAla-mGly-OBzl, having the retro-inverso modification of the Ala-Gly bond, has been determined by x-ray diffraction analysis. The crystals are orthorhombic, space group P2(1)2(1)2(1) with a = 6.539, b = 14.721, c = 17.101 Angstrom, z = 4. The structure was solved by direct methods and refined with anisotropic thermal factors to a final R value of 0.067 for the 947 observed reflections.