ANTI-ENZYME IMMUNITY 179 



ents of normal serum by electrophoresis in the Tiselius apparatus. 

 The inhibitor was found primarily in the albumin fraction and the 

 antiproteinase antibody in the globulin fraction. 



Smith and Lindsley (1939) likewise found that while the trypsin 

 inhibitor in normal serum had no inhibitory action on the proteinases 

 of pathogenic CI. histolyticum, CI. welchii and CI. oedetnatis-maligni, 

 antiserum against the enzyme of CI. histolyticum strongly inhibited 

 the enzyme activity. Immune sera against the enzymes of the latter 

 two organisms were not prepared. 



b. The Nature of the Trypsin Inhibitor in Egg White. Balls and 

 Swenson (1934; see also Balls and Hoover, 1940) isolated an in- 

 hibitor present in egg white; the purer form dialyzed slowly through 

 collodion. It gave positive biuret and Millon tests, but was negative 

 in a test with sodium nitroprusside, in a Molisch test and with Feh- 

 ling's solution. A solution of 10 mg. per ml. gave no visible precipitate 

 with picric, trichloracetic, tannic acids, or mercuric chloride. With 

 phosphotungstic acid, or with two volumes of saturated ammonium 

 sulfate, a heavy precipitate formed. The total nitrogen content was 

 10.55 per cent; it was resistant to heat. These data show that the 

 properties of the inhibitor are comparable to those of peptone-like 

 substances, or to the trypsin inhibitor found in pancreas (Kunitz and 

 Northrop) or in blood serum (Schmitz). 



Balls and Swenson (1934) stated that they had corroborated the 

 earlier findings of Delezenne and Pozerski (1903) that this inhibitor 

 combines with kinase, because additional amounts of kinase decrease 

 the inhibition. Furthermore, they found that the reversal of inhibition 

 by kinase becomes more marked as the amount of inhibitor is de- 

 creased. On the other hand, additional amounts of inactive enzyme 

 (trypsinogen or protrypsin) have also the effect of removing the inhi- 

 bition. The inhibition is therefore a reversible reaction. 



The interpretation of the above mentioned reactions was based on 

 the then current idea that "trypsin-kinase" was a definite compound. 

 Since the publication of the above paper, various enzyme components 

 of pancreatic extracts have been obtained in crystalline form and 

 studied for their interactions (Kunitz, 1939; Kunitz and Northrop, 

 1936). The results of these studies may be compared to those ob- 

 tained by Balls and Swenson with the inhibitor from egg white. 



According to Kunitz and Northrop (1936) and Northrop (1939) 



