Binding affinity of bicarboxylate ions for cobalt (II) bovine carbonic anhydrase

The affinity of bicarboxylate ions (from oxalate to glutarate) for cobalt (II) bovine carbonic anhydrase has been investigated and compared with that of acetate and propionate. The oxalate ion shows a much greater affinity for the enzyme than acetate, whereas the other bicarboxylate ions have very little tendency to bind the enzyme. In every case, and particularly for the oxalate, the apparent affinity constants dramatically increase with decreasing pH. On the basis of the electronic spectra a five-coordinate structure is proposed for all of the above derivatives. Carbon-13 NMR data have been discussed in terms of the oxalate ion chelating the metal ion and/or interacting with the wall of the active cavity.

Interactions between alpha-amino acids and cobalt(II) bovine-carbonic anhydrase

The results of a study on the interaction between cobalt(II) bovine carbonic anhydrase and the alpha-amino acids L(+) and D(-)alanine, glycine and betaine are reported. L(+)alanine and glycine have been found to have larger affinity for the enzyme than D(-)alanine whereas no sizable affinity is shown by betaine. The electronic spectra indicate that these systems are similar to that containing the acetate ion. Utilizing the inhibition properties of L(+)alanine at various pH an analysis of the species involved in the inhibition reaction is presented.

Interaction of cobalt-bovine carbonic anhydrase with the acetate ion

The visible spectra of solutions of cobalt(II) bovine carbonic anhydrase (carbonate hydro-lyase, EC 4.2.1.1) with increasing amounts of acetate have allowed the determination of the apparent inhibition constants and of the extrapolated limit spectra of the completely bound enzyme. The electronic spectra have been interpreted on the basis of the presence of five coordinate adduct species. 13C and 1H NMR spectra have also been recorded and discussed on the basis of the metal enzyme-acetate type of interactions. Titrations by means of NMR spectroscopy of the acetate-cobalt(II) bovine carbonic anhydrase with p-toluenesulfonamide and azide indicate the existence of two binding sites for the acetate group.