Variants of normal human alpha2-macroglobulin. Immunoelectrophoresis and enzyme-binding effect.

Three phenotypical variants of normal human serum alpha2-macroglobulin revealed by immunoelectrophoresis and specific antibodies obtained in rabbits are presented. The variants are characterized by differences in electrophoretic mobility: one being fast, one slow, and one of an intermediate rate. To find out possible differences with respect to the effect of the trypsin and chymotrypsin on the three variants, they were treated with the enzymes before immunoelectrophoresis. Migration was accelerated in all cases, after complexing with the enzymes, but the differences in the relative positions of the variants were maintained. The trypsin- and chymotrypsin-binding capacities of these three forms seem to differ, as suggested by the results presented in this report.