Determination of a glycosyl subunit of human serum albumin by concanavalin A-sepharose.

A new procedure has been devised for the isolation of a glycosyl subunit of albumin from human serum. After the selective removal from serum proteins with affinity chromatography on Blue-Sepharose CL-6B, albumin was applied to a column of concanavalin-A Sepharose which resolved the protein in two subunits with different specific colour activity for carbohydrates, as tested with thiobarbituric acid assay. The glycosyl albumin bound to concanavalin-A Sepharose was homogeneous when examined by immunoelectrophoresis and sodium dodecyl-sulphate polyacrylamide electrophoresis, whereas it showed a microheterogeneity when tested by isoelectric focusing. The procedure was applied to a model system as well as to serum from normal and diabetic patients.