Nickel carbonic anhydrase: a re-examination of the electronic spectra with the help of CD spectra

Abstract

The electronic and CD spectra of nickel(II)-substituted bovine carbonic anhydrase, and of its adduct with p-toluenesulfonamide, have been re-recorded in the rangers 8–30 X 10 3 cm −1 and 10–30 X 10 3 cm −1, respectively. Although the positions of the main absorption are consistent with six-coordination of the metal ion in the enzyme active site, their relative intensity and the detection of other transitions suggest the operativity of strong low-symmetry components. Therefore five-coordinated rather than octahedral chromophores have been considered in order to account for the observed spectroscopic properties.