Metallocarbonic anhydrases: optical rotatory dispersion and circular dichroism.

Abstract

The optical rotatory dispersion and circular dichroism (CD) of Co(II) and Cu (II) carbonic anhydrase and a variety of inhibitor complexes are presented. The CD spectra reveal that the chromophores introduced by these metal ions are more complex than indicatedby the visible absorption spectra alone. The Co chromophore is associated with a number of near UV absorption bands in addition to the visible bands. The CD spectra of all the inhibitor complexes are a complex array of overlapping positive and negative bands, whose rotatory powers are markedly altered by the intrinsic structure of the protein (indicated by large differences between isozyme variants of carbonic anhydrase) as well as by the nature of the extrinsic ligands, the anions and sulfonamides.