376 IMMUNO-CATALYSIS 



these three, the most active pair is found to be the glutamic-aspartic 

 transaminase system (Cohen, 1942; Braunstein, 1947), 



In bacteria, the following principal transamination reactions are 

 reported (Lichstein and Cohen, 1945): 



(1) lC+)-glutamic acid+oxalacetic acid-^ 



a-ketoglutaric acid+l(— )-aspartic acid 



(2) 1 ( — )-aspartic acid+a-ketoglutaric acid^ 



1 ( + )-glutamic acid+oxalacetic acid 



(3) a-ketoglutaric acid+l( + )-alanine— >lC + )-glutamic acid+pynivic acid 



Both reactions (2) and (3) are said to proceed very slowly as com- 

 pared with reaction (1) which shows activity of a high order of 

 magnitude. They found that E. colt, B. dysenteriae (Shiga), B. typho- 

 sus, B. proteus, B. fyocyaneus, Azotohacter vinelandii, Staphylococcus 

 aureus and alhus, CI. welchii, Streptococcus hemolyticus and viridans, 

 and Pneumococcus, Type I, were active in catalyzing these reactions. 



The data at present are inadequate concerning the question of 

 whether or not transamination reactions involve reversible oxidative 

 deamination. Following the work of Snell (1945), and Schlenk and 

 Snell (1945) indicating a role for pyridoxal and pyridoxamine in 

 transamination, Lichstein, Gunsalus and Umbreit (1945, 1947) dem- 

 onstrated that pyridoxal phosphate functions as the coenzyme of 

 glutamic-aspartic transaminase of bacterial cells. 



Snell (1945) postulated that the prosthetic group, pyridoxal, of 

 transaminase acted by alternately accepting and donating amino 

 groups, but it has not as yet been established conclusively that this 

 cyclical amination and deamination of the prosthetic group, pyridoxal 

 phosphate, occurs during the process of transamination. Umbreit, 

 O'Kane, and Gunsalus (1948) presented data in favor of and against 

 this concept. In their study, the activities of pyridoxal phosphate and 

 "pyridoxamine phosphate" on transamination reactions were compared. 



In the generation of pyruvate from carbohydrate metabolism, and the 

 initiation of the tricarboxylic acid cycle via pyruvate, three most im- 

 portant a-keto acids are formed. From these, three reactive amino acids, 

 alanine, aspartic acid and glutamic acid, are formed. These amino acids 

 in conjunction with a-keto acids derived by various means can serve as 

 a basis for the synthesis of other amino acids by any one of the processes 

 outlined above, paving the way for the synthesis of proteins and other 



