362 



Studies on Enzyme Action. 



is reason to believe that we always deal with a variety of enzymes when 

 using natural products. 



Bayliss appears to have been impressed by the contentions advanced in a 

 lengtby degree dissertation published in the 'Zeitschrift fur physikalische 

 Chemie '* by Fajans, who bases his contentions on experiments which appa- 

 rently have no connexion with the action of enzymes. 



Bredig and Fajans have found that, on heating the two isomeric optically 

 active d and I camphorcarboxylic acids with an optically active base, the one 

 acid undergoes decomposition into camphor and carbon dioxide more readily 

 than the other. It is assumed by Fajans that the optically active base 

 functions as a catalyst — just as an enzyme does — and that whilst both 

 acids are decomposed, the base acts preferentially, so that one acid is 

 decomposed by it to a greater extent than the other acid. The assumption 

 that in such a case the action is catalytic and comparable with that exercised 

 by an enzyme is purely gratuitous, however. 



Fajans himself admits that the salt is the substance that undergoes 

 decomposition. As the salts formed from two corresponding optically 

 active acids and an active base would not be optical opposites, the base, 

 presumably, being differently situated in the two salts, would exercise a 

 different attractive force in loosening carbon dioxide ; it is not surprising, 

 therefore, that the two salts undergo decomposition at different rates. 



Fajans asserts that every order of difference is to be found in the 

 behaviour of an enzyme towards optical isomers but this is definitely not 

 true. A number of the cases to which he refers are not to the point — thus 

 it is in no way established that the oxydases are enzymes and the fact that 

 moulds are able to utilise both components of racemic amino-acids is easily 

 accounted for in view of the ease with which these acids are racemised by 

 ordinary agents. In the case of lipase, there is no reason to correlate the 

 activity of the " enzyme " with optical activity — it is a selective agent only 

 in the sense that it is a specific hydrolyst of ethereal salts of carboxylic 

 acids. In point of fact, the only definition that can be given, at present, of 

 an enzyme that will separate enzymes from other hydrolytic agents is one 

 which involves the assumption that they act selectively. 



* 1910, vol. 73, pp. 25—96. 



