The inactivation of trypsin by heat

Abstract

THE study of the heat-inactivation of trypsin contained in a crude extract of dried pancreas gland powder is complicated by the "spontaneous activation" which occurs in such extracts. This transformation takes place in aqueous extracts of dried pan- creas powder, or in the dried powder itself on prolonged storage. As a conse- quence, in an aqueous extract of dried pancreas powder maintained at constant temperature two processes occur, heat-inactivation of the trypsin and simul- taneously "spontaneous activation" of the enzyme. Thus, if the trypsin content of the extract be measured from time to time by hydrolysis of a suitable protein, there may be, instead of the decrease to be expected from heat-inactivation of the enzyme, an apparent increase in trypsin content, if it so happens that the "spontaneous activation" effect preponderates over the heat inactivation. Furthermore, Waldschmidt-Leitz has indicated that trypsin associated with its activator is less stable than the enzyme alone. In view of this the main experiments described in this paper have been carried out with a purified extract of the dried pancreas powder, in which the trypsin is free from enterokinase and its pre-stage.