42 PROTEOLYTIC PANCREATIC FERMENT 



sition. A number of authors would relate the adsorptive 

 readiness of enterokinase (as in its ready fixation by 

 fibrin) with its action, and believe that, in the same way as 

 in haemolysis complement is fixed to a red blood cell by the 

 intermediation of an amboceptor, trypsinogen is fixed to the 

 protein molecule as complement by the binding power of 

 enterokinase (as amboceptor) . Enterokinase is a thermola- 

 bile substance; but 0. Cohnheim's observation that it is 

 soluble in 90 per cent, alcohol is clearly not in harmony with 

 the idea that it is of the nature of an enzyme. It is scarcely 

 believed any longer that enterokinase is derived from 

 leucocytes ; it is apparently directly produced from the cells 

 of the intestinal mucous membrane, although there seems to 

 be some active material of similar character also present in 

 leucocytes at times. 



Activation of Trypsinogen by Calcium Salts and Similar 

 Substances. Besides enterokinase a considerable group of 

 other agents is known to be capable of activating trypsino- 

 gen. Calcium salts particularly have been the object of care- 

 ful investigation by Delezenne in their marked relations with 

 trypsinogen. Activation of an inactive dyalized pancreatic 

 juice, after the latter, mixed with a salt of calcium, has been 

 kept in an incubator for a number of hours, may result sud- 

 denly, as if explosively ; if paraffined tubes have been used 

 activation by calcium salts may be postponed for some 

 days. 20 



With special precautions activation of trypsinogen may 

 be induced by quite a variety of colloids (as by toluidin blue) . 

 It is therefore scarcely remarkable that the expressed juices 

 from various organs, milk and similar substances, have been 

 found capable of inducing the same result. Even bacteria 

 can convert trypsinogen into trypsin ; the author has in an 

 earlier volume (cf. Vol. I of this series, Chemistry of the 



20 Cf . also J. Wohlgemuth ( Experimental Division of the Pathol. Institut., 

 Berlin), Observations upon Human Pancreatic Fluid, Biochem. Zeitschr., 39, 

 302, 1912. 



