The microheterogeneity of serum alpha 1-antichymotrypsin revealed by interaction with concanavalin A in crossed immunoaffinoelectrophoresis and in affinity chromatography.

In crossed immunoaffinoelectrophoresis with free concanavalin A in the first dimension, human serum alpha 1-antichymotrypsin, purified or in whole serum, exhibited four peaks in presence of 0.02 M alpha-methyl-D-glucoside added to the second-dimensional gel. alpha 1-Antichymotrypsin purified from the serum of a single healthy donor was separated by affinity chromatography into three fractions on a laboratory-prepared concanavalin A-Sepharose 4B column: a pass-through fraction, a retarded fraction and a bound fraction, eluted from the column on addition of sugar to the buffer. These three fractions were analyzed by crossed immunoaffinoelectrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing before and after desialylation. The results of electrophoresis as well as chemical analyses indicate that these microheterogeneous forms carry glycans with decreasing degrees of branching from the concanavalin A-pass-through form to the concanavalin A-bound form. This approach represents a first step towards the elucidation of the molecular basis of the microheterogeneity of alpha 1-antichymotrypsin.