Carbon-13 longitudinal relaxation times of acetate ion in the presence of metal-substituted bovine carbonic anhydrases

Abstract

Longitudinal relaxation times T₁ have been determined for both carbons of ¹³C-enriched acetate in the presence of bovine apo-, zinc(II), cobalt(II), and manganese(II) carbonic anhydrase, and the factors affecting them have been analyzed. The existence of a further interaction besides the binding at the metal atom has been confirmed by measuring T₁ in the presence of excess of a strong inhibitor like toluene-p-sulphonamide. By use of the Solomon–Bloembergen analysis, distances and orientations of acetate with respect to the metal ion have been estimated both at the metal binding site and when unco-ordinated.