The enhancing effect of gelatin on aprotinin activity.

Following preincubation of aprotinin with gelatin, the inhibitory effect on the trypsin activity was enhanced under the same condition as in the case of enhanced antigen-antibody reaction of aprotinin in gel in the presence of gelatin. In the immunochemical titration of aprotinin, gelatin treatment decreased the value of the equivalence point of aprotinin. Immunoprecipitation of aprotinin preincubated with or without gelatin adjusted to equal activity per unit volume resulted in overlapping equivalence points. These data suggest that the increase in aprotinin activity in the presence of gelatin is due to increase in the active form of aprotinin.