Investigation of cobalt(II) substituted carboxypeptidase a interacting with azide and cyanate ions

Abstract

Cobalt(II)-substituted carboxypeptidase A has been found to reversibly bind N3 − and NCO −, but not NCS −, in the pH range 5–10, thus including the pH range of activity of the enzyme. The pH dependence of the anion binding constant is affected by two ionizations, which are assigned as those regulating k cat and K M. The electronic and 1H NMR spectra are consistent with a substantially pseudotetrahedral geometry of the anion derivatives.