X-ray study of the rubidium salt of ADP

Abstract

Enzymatic reactions involving ATP and ADP require various metal ions as cofactors for catalytic activation. To understand the molecular mechanisms involved in these reactions it is important to know both the detailed geometry of these molecules and the way in which they bind to metal ions. Although numerous physical and chemical studies have been undertaken, particularly of divalent metal complexes in solution, the conformational and electronic aspects of these complexes are not fully understood. In the solid state, crystallographic studies have led to deductions on the conformations of ATP and ADP when bound to enzymes (refs 1–3 and H. C. Watson, personal communication) but the only crystal structures so far determined to atomic resolution are of the disodium salt of ATP and the monorubidium salt of ADP. The latter structure has so far only been published in part although some of its molecular features were reviewed recently.