Preparation of specimens of human serum gamma-globulin modified by copper and zinc and its immunochemical characteristics.

Specimens of human serum gamma-globulin modified by molar excess of copper and zinc cations were obtained by molecular ultrafiltration. Conformation characteristics of the protein were determined by UV spectrophotometry. Immunochemical study included radial immunodiffusion test and direct and sandwich enzyme-linked immunosorbent assay.

Reactions between human serum gamma-globulin and zinc cations.

Interactions of human serum gamma-globulin with zinc cations in solution were studied by differential spectrophotometry in UV light. Supraphysiological concentrations of zinc caused an increment in optical density of protein solution reflecting the effect of gamma-globulin saturation with the metal. Zinc concentrations below physiological led to hypochromism in the protein absorption spectrum.