Preparation and X-ray Analysis of Crystals of Azido- and Chlorocobalamin Containing LiCl: A Structural Model for the Interactions of the Corrin Ring with Ionic Species

Abstract

High-resolution X-ray structure determinations of chloro- and azidocobalamin·2LiCl, crystallized from concentrated aqueous LiCl solutions, show lithium cations coordinated to the phosphate O atom and to the amidic O atoms of the corrin side chains, and chloride anions held by H-bonds to the corrin amidic N atoms. The structures of the two compounds represent the first structural picture of the interactions of the cobalamin molecule with ionic species.