112 IMMUNO-CATALYSIS 



Bergmann, 1939), however, Butler's results do not indicate that the 

 hydrolysis of amide bonds occur to any significant extent during the 

 activation process. In view of these experimental material, Jacobson 

 does not seem to favor, on the basis of the fonnulation of Mirsky 

 and Pauling, that chymotrypsinogen contains or consists of one unin- 

 terrupted peptide chain. Assumption is made that if proteins contain 

 several peptide chains, the breaking of about four peptide bonds in 

 chymotrypsinogen with the result of an increase of six to nine titratable 

 groups when a-chymotrypsin is formed, may be explained. This could 

 result from the proteolytic rupture of peptide bonds in the peptide 

 chain or chains of chymotrypsinogen and of the proteins (one of which 

 is TT-chymotrypsin) which are intermediaries of chymotrypsinogen and 

 a-chymotrypsin, without necessitating the formation of non-protein- 

 nitrogen. This, however, leaves unexplained the origin and nature of 

 2.7 per cent non-protein-nitrogen formed during these reactions, part 

 of which at least can be accounted for as ammonia nitrogen as Butler 

 (1941) has found. 



Jacobson arbitrarily chooses a molecular weight of 36,000 (36,700 

 by Brand and Kassel, 1941) for chymotrypsinogen. Since he found the 

 production of 2.7 per cent non-protein-nitrogen during the conversion 

 of chymotrypsinogen into a-chymotrypsin, the molecular weight of 

 the latter was calculated to be at least 35,000. These values are basically 

 diJfferent from those of 32,000 to 36,000 for chymotrypsinogen, and 

 40,000 for a-chymotrypsin as measured by Kunitz and Northrop 

 (1935), and Kunitz (1939). Consequently, Jacobson's chymotrypsin 

 would appear to be a derivative of diminished molecular weight, and 

 that of Kunitz and Northrop a chymotrypsinogen derivative of about 

 1 1 per cent increased molecular weight. This discrepancy may, how- 

 ever, be due to the inconstancy of the molecular state of the active 

 enzyme. 



In connection with the above observations of Jacobson, it is to be 

 noted that earlier Kunitz (1938) had prepared crystalline a- and y-chy- 

 motrypsins from chymotrypsin. These two proteins did not differ in 

 activity from the parent chymotrypsin of 40,000 molecular weight. 

 The molecular weights of a- and y-chymotrypsins were reported to be, 

 respectively, 27,000 and 30,000. It is interesting that a non-essential 

 part or component corresponding to a molecular weight of 10,000 to 

 13,000 can be split off the chymotrypsin molecule (or complex) with- 



