Effect of metallic cations on human serum: Study by starch-gel electrophoresis: I. Effect of Pb ++, Cu ++, and NH 4+

Abstract

When Pb(NO 3) 2 or CuSO 4 is added to human serum, the amount of precipitate increases with increase in the concentration of the cation. The supernatant was analyzed by starch-gel electrophoresis. Some protein components of human serum are precipitated at lower concentrations and some resist precipitation even at higher concentrations of a cation. The precipitability of a component depends on the nature of the cation. The main components in the supernatant obtained when serum diluted 50% is made 30 m M in Pb ++, are transferrin and γ-globulin. Almost all the γ-globulin is precipitated when serum diluted 50% is made 6 m M in Cu ++; almost all the proteins are precipitated when the final concentration of Cu ++ is 20 m M. There are two interesting phenomena. One is that the zone of a particular component disappears abruptly at a certain concentration of cation, while a new zone appears, and probably indicates that the component is modified by the cation with a change in mobility. The other is that the intensity of staining of a particular component increases with increase in the cationic concentration. An explanation is that the metallic cation (Pb ++ or Cu ++) bound to the protein binds dye (e.g. protein −—Pb ++—dye −). Human serum albumin recrystallized three or four times by ammonium sulfate salting-out was analyzed by starch-gel electrophoresis. There were four zones besides the albumin zone. The pattern is similar to that obtained from human serum albumin prepared by cold ethanol fractionation. Human serum albumin extracted from the albumin zone of “starch-block” electrophoresis was shown by starch-gel electrophoresis to be more homogeneous than albumin prepared by salting-out.