The isolation and properties of a fragment of bovine-serum albumin which retains the ability to combine with rabbit antiserum

Abstract

Chymotryptic digestion of bovine - serum albumin in a dialysis sac produced a diffusible digestion product which retained the power to combine with rabbit antibovine-serum albumin. This product was isolated, principally by zone electrophoresis. The N-terminal amino acid is phenylalanine. The molecular weight of the active fragment is about 12,000, but it readily dimerizes, probably through a free sulfhydryl group. The reaction of this substance with different rabbit antisera was studied and the results used to classify the different types of antibody which appear to be present in all antisera. This active fragment can provoke anaphylactic shock in a guinea pig passively immunized by injection of rabbit anti-bovine-serum albumin.