Transamination 



PHILIP p. COHEN 



University of Wisconsin 



IN VIEW OF THE FACT that Braunstciii (1) has recently reviewed in 

 some detail the results of experiments on transamination in his 

 laboratory, no attempt will be made here to present tabular 

 details of these studies. Unfortunately most of the publications 

 issued since the review by Braunstein have not been available to 

 the writer except in Chemical Abstracts, to which reference is made 

 in the bibliography. 



Many of the papers published in this field, being of a preliminary 

 sort, are of uncertain value. Most investigators seem to be interested 

 merely in demonstrating that transamination does or does not occur 

 in a given tissue. Unfortunately the analytical methods usually em- 

 ployed permit little more than a qualitative demonstration of the 

 reaction. Thus, in spite of a widespread interest in transamination, 

 few reliable quantitative data are available that can be used for 

 evaluating the role of this reaction in intermediary metabolism. 



Types of Transamination 



Transamination is a reaction between an alpha-amino and an 

 alpha-keto acid resulting in the transfer of the amino group from 

 the former to the latter. When the reaction is enzymatically cata- 

 lyzed, the end products formed are an alpha-amino and an alpha- 

 keto acid, the former corresponding in structure to the original 

 alpha-keto acid, and the latter to the original alpha-amino acid 

 (Reaction 1). 



(1) Ri-CH(NH2)-COOH-f-R.COCOOH^RrCOCOOH 



+ R2-CH (NH2)-COOH 



When carried out at boiling temperatures, the end products of 

 transamination are usually an aldehyde corresponding to the 

 original alpha-amino acid, an alpha-amino acid corresponding to 

 the original alpha-keto acid, and carbon dioxide (Reaction 2). 



(2) Ri-CH(NH2)COOH + RrCOCOOH^R,-CHO 



-f- RjCHNHj-COOH -f- CO2 



Reaction 2 has been studied in some detail by Herbst, who has 

 recently reviewed this subject (2). 



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