Stereochemical criteria for polypeptides and proteins : VI. Non-bonded energy of polyglycine and poly--alanine in the crystalline [beta]-form

Abstract

This paper describes calculations on the packing energy in the crystal structures of [beta]-forms of polyglycine and poly--alanine. It is shown that the non-bonded interactions between [beta]-chains, in a pleated sheet structure, yields a minimum energy when the interchain spacing is about 4.8 A, which is well-suited for the formation of interchain NH [middle dot][middle dot][middle dot] O hydrogen bonding. The attempts made to deduce the crystal structures of [beta]-forms of polyglycine and poly--alanine are also described.