A systematic approach to isomorphous replacement using a series of simple charged mercurials

Three novel mercury derivatives bearing different electronic charges have been synthesized and used to prepare useful heavy atom derivatives of crystals of glycogen phosphorylase a. While exhibiting some common binding sites on the exterior of the molecule, their internal binding sites are determined primarily by their charge as predicted. Their ease of preparation and general applicability makes them useful candidates for the preparation of heavy atom derivatives of any protein crystals in X-ray crystallographic studies.