TRANSAMINATION 225 



As can be seen from this scheme, a keto-aldehyde reacts with an 

 amino acid to form a ketonic SchifiTs base. The latter then reacts 

 with glutamic acid via the transamination reaction to yield a pep- 

 tide. Agren (19) has recently published unconvincing evidence in 

 support of this. 



On the basis of the above reaction it would be expected that in 

 tissues where rapid protein synthesis was taking place, e.g., embry- 

 onic and tumor tissue, the transaminase activity would be higher 

 than in normal adult tissues. Actually the reverse has been found 

 to be the case (16). Thus it was observed that in tumors and em- 

 bryonic tissue the transaminase activity was low as compared with 

 normal adult tissues. This apparent inverse relationship between 

 protein synthesis and transamination suggests that the latter re- 

 action may serve as a controlling mechanism in protein synthesis. 



Plant Tissues.— The possible role of transamination in plant pro- 

 tein synthesis is suggested from the following scheme of Virtanen 

 and Laine (41) for leguminous plants: 



SCHEME IV 



Ng ^ Hydroxylamlne^^ 



^(Oxime of Oxalaceiic Acid 



Carbohydrate — ^Oxalacefic Acidj^ +H2 



\ \p 



l(-)Aspar+ic Acid 



+ a Keto Acid 



'Oxalaceiic Acid 



+ a Amino Acid 



Experimental evidence for the above scheme has been reported 

 by Virtanen and Laine (41, 53) and has been critically examined 

 by Wilson (44). However, careful quantitative studies on trans- 

 amination in plant tissues have not as yet been carried out. Until 

 this is done the role of transamination in plant tissues will continue 

 to remain obscure. 



OTHER REACTIONS 



Transamination and Glycolysis— Krehs (54) and Weil-Malherbe 

 (55) observed that glycolysis in retina and brain tissue was in- 



