4 86 SCIENCE PROGRESS 



Dakin and Dudley 1 have obtained this enzyme from various 

 animal tissues, such as the muscle and liver of exsanguinated 

 dogs or rabbits. It possesses the power of accelerating very 

 markedly, even under "in vitro" conditions, the reversible 

 reactions by which methyl and phenyl glyoxal are converted 

 into lactic and mandelic acid respectively. 



CH, - CO - CHO + H.,0 "7* CH3.CHOH - COOH 



Methyl glyoxal. Lactic acid. 



C 6 H 5 - CO - CHO + H,0 "* C 6 H S - CHOH - COOH 



Phenyl glyoxal. Mandelic acid. 



The enzyme is readily obtained in aqueous extract, and the 

 extract loses its activity on being heated to 6o° C. Dakin and 

 Dudley failed to precipitate and separate the enzyme by the 

 addition of alcohol, but they succeeded in obtaining an active 

 preparation by precipitating it with solid ammonium sulphate 

 and then dialysing the suspension in water. 



The wide distribution of this enzyme may be of considerable 

 significance in reference to the inter-relation of carbohydrate and 

 protein metabolism. 



Methyl glyoxal or a closely allied substance is obtained from 

 the action of sodium phosphate on glucose. It is therefore 

 possible to obtain from glucose both organic acids and alde- 

 hydes, and these are bodies from which amino-acids may readily 

 be derived. Thus it may be anticipated that within the living 

 cell alanine may be derived from methyl glyoxal, in much the 

 same manner in which glycine has been obtained from glyoxal. 

 The relation of glucose to amino-acids and to organic acids 

 might then be expressed in the following manner : 2 



Glucose. 



C s H,j,0 6 

 4 t 



Lactic acid. Methyl glyoxal. Alanine. 



CH s .CH.OH.COOH *~ CH 3 . CO . CHO ~* CH 3 . CH . NH, . COOH 



The distribution of this enzyme is clearly of importance to 

 the animal physiologist and may account for the production of 

 glucose in the glycosuric organism, but its distribution in the 

 plant must be known before its significance in plant metabolism 



1 Dakin and Dudley, Joum. Biological Chem. xiv. p. 155, and xiv. p. 423. 

 3 Ibid. xv. p. 127, 191 3. Alanine has not yet been synthesised directly from 

 methyl glyoxal. 



