A Multinuclear Ligand NMR Investigation of Cyanide, Cyanate and Thiocyanate Binding to Zinc and Cobalt Carbonic Anhydrase

BERTINI, I; LUCHINAT, C; PIERATTELLI, R; ALEJANDRO JOSE VILA

INORGANIC CHEMISTRY

AMER CHEMICAL SOC

Año: 1992 vol. 31 p. 3975 - 3979

0020-1669

Relaxation rate measurements on I3C-enriched NCO-, NCS-, and CN- as well as on ISN-enriched NCS- have been performed in presence of cobalt(I1)-substituted carbonic anhydrase (CA). It is shown on firm basis that NCOand NCS- do bind cobalt although with different geometries. The data of the NCS- case are consistent with the available X-ray data. No information could be obtained on CN- because of slow exchange between its free and enzyme-bound forms. I3C relaxation measurements have been performed on 13C15N- in the presence of 67ZnCA. The large quadrupolar moment of 67Zn(II) induces relaxation on 13C, thus showing that there is direct coordination. NMR spectroscopy provides strong important pieces of information on the present debate on the way of binding of anions to carbonic anhydrase.