The binding of zinc(II) to Mung Bean Nuclease. A voltammetric study

Binding of zinc to Mung Bean Nuclease was investigated by anodic stripping voltammetry and cyclic voltammetry. These methods rely on the direct monitoring of the oxidation current of zinc in the absence and presence of Mung Bean Nuclease. Titration curves of Zn2+ with the enzyme were obtained in concentrations ranging from 1.08x10(-9) to 1.07x10(-8) M and 1.16x10(-8) to 1.04x10(-7) M. The acquired data were used to calculate the dissociation constant and the stoichiometry of the complex. The binding sites of zinc in the Mung Bean Nuclease molecule were investigated using cyclic voltammetry. Two types of binding sites for zinc were identified and were attributed to a mononuclear exposed zinc-binding site with catalytic function and to an inaccessible binuclear zinc-binding site with structural functions. (C) 2003 Elsevier Science Inc. All rights reserved.