ANTIBODIES AGAINST RESPIRATORY ENZYMES 375 



glycine. Fresh cell-suspensions were found not only capable of oxida- 

 tively deaminating alanine, serine, threonine, glutamic acid and aspar- 

 tic acid to their corresponding a-keto acids, but the latter were further 

 oxidized. 



The equivalent of the Proteus enzyme was found in washed cell 

 suspensions of Aerohacter aerogenes and Pseudomonas fjocyaneus, but 

 not in those of E. coli, Streptococcus hemolyticus, Di'plococcus 'pneu- 

 moniae, Salmonella paratyphi, Bacillus suhtilis. Staphylococcus aureus, 

 and Sarcina lutea. 



It is apparent that a-keto acids derived in a manner described above 

 can serve as bases for the synthesis of different a-keto acids which can 

 be aminated forming new amino acids. 



b. Synthesis of Amino Acids by Transamination. Amino acids can 

 also be synthesized by the transfer of an amino group from an amino 

 acid to an a-keto acid in the following manner : 



C 1 ) HOOCCH(NH2)CH2COOH+HOOCCH2CH2COCOOH^ 

 Aspartic acid a-ketoglutaric acid 



HOOCCOCHXOOH-(-HOOCCH2CH2CHCNH2)COOH 

 Oxalacetic acid Glutamic acid 



(2) HOOCCH2CH2CHCNH2)COOH-FCH3COCOOH^ 



Glutamic acid Pyruvic acid 



a-ketoglutaric acid-FCH3CH(NH2)COOH 

 Alanine 



Two separate enzyme systems mediate the above reactions. When 

 these two enzyme systems are present as a mixture, the reaction, 



(3) Aspartate -[-pyruvate ^ oxalacetate-1- alanine 



also takes place (Green, Leloir and Nocito, 1945; O'Kane and Gun- 

 salus, 1947). These investigators did not find an enzyme system specific 

 for reaction (3). 



It is, therefore, claimed that there are two principal transaminases: 

 (1) the aspartic-glutamic enzyme system, and (2) the alanine-glutamic 

 enzyme system, which function reversibly as indicated above. (For ex- 

 tensive discussion of transamination reactions see Cohen, 1942, and 

 Braunstein, 1947.) 



In the animal system, the most active transamination enzyme system 

 is claimed to comprise the three paired reactions described above. Of 



