Spectroscopic characterization of nickel(II) carboxypeptidase

Abstract

The electronic and ¹H NMR spectra of nickel-substituted carboxypeptidase have been measured and discussed in the light of the available X-ray data. The interaction with D-phenylalanine has been investigated as well as that with azide. It is proposed that D-Phe binds first at a non-metallic site, probably Arg-145, and then to the metal. The behaviour of L-Phe is more complex. Azide binds at the metal in the presence of the amino acid. These results are similar to those obtained for the parent (zinc) and cobalt-substituted enzymes. Implications for the enzymatic mechanism are discussed.