IMMUNOCHEMICAL STUDIES WITH CHYMOTRYPSINOGEN A.

Antiserum prepared by immunization of rabbits with chymotrypsinogen A reacted in equal titre with the proenzyme and alpha, beta, delta and gamma chymotrypsin in serological tests. Inactivation of the four enzymes by diisopropyl-fluorophosphate did not diminish their precipitability. Immunodiffusion tests in gel plates with the proenzyme produced a single precipitin band which merged without spur formation with the bands produced by each of the native and inactivated enzymes. The antiserum partially inhibited activation of the zymogen by trypsin. The proteolytic activity of each of the four chymotrypsins was also inhibited by the antiserum.