138 Scientific Proceedings (39). 



86 (496) 



A modified method for the clinical estimation of pepsin. 



By WILLIAM C. ROSE. (By invitation.) 



[From the Sheffield Laboratory of Physiological Chemistry, Yale 

 University, New Haven, Connecticut.] 



A globular preparation well adapted for the purposes of the 

 Jacoby-Solms pepsin test can be made cheaply from the ordinary 

 garden pea, Pisum sativum. 1 This protein dissolves practically 

 completely in ten per cent, sodium chloride solution, and after 

 slight acidification with hyrochloric acid, yields a turbid solution. 

 For the estimation of pepsin, 0.25 gram globulin of the pea is 

 dissolved in 100 cubic centimeters of ten per cent, sodium chloride 

 and filtered. One cubic centimeter portions of the clear filtrate 

 are introduced into a series of small test-tubes, and each portion 

 treated with one cubic centimeter of 0.6 per cent, hydrochloric 

 acid. After the development of the turbidity, increasing amounts 

 (0.1 to 1.0 cubic centimeter) of neutralized, five-times-diluted 

 gastric juice are added to the tubes. Boiled, diluted gastric juice 

 is then added until the volume in each tube is 3.0 cubic centimeters. 

 Digestion is allowed to go on for fifteen minutes in a water-bath 

 at a temperature of 50°-52° C. The enzyme content is expressed 

 by the number of cubic centimeters of the standard protein solu- 

 tion that would be digested until perfectly clear by one cubic 

 centimeter of the undiluted gastric juice, under the standard con- 

 ditions of time and temperature. 



The advantages of the modification over the original Jacoby- 

 Solms procedure are: first, the reduction of the time necessary for 

 the determinations— from three hours to fifteen minutes; second, 

 the use of a perfectly non-toxic substrate; and third, the estima- 

 tion of the proteolytic activity independently of the variations 

 in acidity, thus eliminating an error in the original method. 



^he method of preparation of the globulin together with a detailed description 

 of the modified pepsin test will appear in an early issue of the Archives of Internal 

 Medicine. 



