Binding of Au(CN)2- and Pt(CN)4-2- to horse liver alcohol dehydrogenase. A 35C1NMR relaxation study.

The binding of Au(CN)2- and Pt(CN)4-2- ions to the coenzyme binding site of horse liver alcohol dehydrogenase (alcohol : NAD+ oxidoreductase EC 1.1.1.1) has been studied by 35C1 nuclear magnetic relaxation. Longitudinal relaxation rates were analyzed in terms of a simple model and binding constants for Au(CN)2-, Pt(CN)4-2- and C1- were estimated. From a comparison between transverse and longitudinal relaxation rates the correlation time and the quadrupole coupling constant of bound chloride ion were obtained. The quadrupole coupling constant estimated from a simple electrostatic model for chloride ion interacting with an arginine group agrees with the experimental value.