Conformation of the arginine side-group and its variations

Abstract

Recent crystal structure determinations of two modifications of L-arginine hydrochloride, each containing two independent molecules, and of L-arginine base, reveal a close similarity in the covalent bond lengths and bond angles of the arginine molecules in the different crystals. But a study of the molecular conformation shows that it is quite different about the bonds joining the different atoms. Although the conformations of the atoms directly connected to the backbone part, NC_αC', are nearly the same, side-group conformations are entirely different, jutting out in three nearly perpendicular directions in different structures. This brings out the importance of studying a number of derivatives of amino acids and simple peptides, to obtain knowledge regarding the common types of side-group conformations.