STRUCTURE OF A 1-1 COMPLEX BETWEEN L-ASP-L-PHE AND L-HIS-GLY

Both molecules occur in slightly folded conformations, characterized b y psi2 = -93.7-degrees in L-His-Gly and an unusual psi2 = 60.2 in L-AS p-L-Phe. The peptide linkage Of L-His-Gly displays a substantial devia tion from planarity with omega1 = -163.5-degrees. The crystal packing is arranged in thick hydrophilic layers separated by hydrophobic sheet s composed Of L-Phe aromatic side chains. There are numerous hydrogen bonds, including an extremely short contact [O...N = 2.532 (6) angstro m] between the ionized L-Asp and L-His side chains.