1912.] 



Studies on Enzyme Action. 



367 



CH.,.OH 



O.C 6 H u 5 



Salicin. 



The slight activity towards prunasin of Asperula odorata, Galium verum, 

 Isatis tinctoria and Eubia tinctoria is explicable from this point of view, as 

 the enzymes which these plants contain are probably active only towards the 

 glucosides by which they are severally characterised — coumarin-glucoside 

 indican and ruberythrinic acid. 



On the other hand, it is conceivable that a difference such as is here 

 referred to may be sufficient to affect an enzyme compatible with the 

 glucose group in the glucoside and also immediately compatible with the 

 group associated with glucose in a particular glucoside. Thus the group 

 CO.OCH3 in gaultherin may be sufficiently different from the group CH 2 .OH 

 in salicin to make it impossible that the enzyme naturally associated with 

 the one compound should be able to enter into such relationship with the 

 other compound that it can promote its hydrolysis. 



The following values obtained with arbutin are of interest from this point 

 of view : — 



Percentage hydrolysed. 



Arctostaphylos uva-ursi (bearberry) 2 - 5 



Arbutus unedo 



Epilobium angustifolium (Swiss) 22 - 5 



Salix rubra (1911) 13-7 



It may be, of course, that in some cases, the material at our disposal has not 

 been gathered at the right season and has contained little or no enzyme. To 

 make the work complete the influence of season must be taken into account. 



Obviously, a vast amount remains to be done before these and other 

 similar problems have been solved. When suitable materials have been 

 discovered, it will be necessary to institute a close comparative study of 

 the action of the enzymes on a variety of materials. Sufficient has been 

 done to show that the method is .one that can be applied generally. 



Thus far our remarks have been directed mainly to the evidence the 

 results afford as to the character of the enzymes present in various plants. 

 There are other points to which it is desirable to refer briefly in conclusion. 



The results quoted are in no way representative of Prunus laurocerasus ; 

 younger leaves are more active towards prunasin. We are making a special 

 study of this leaf with a view to determining the variations to which it is 

 subject during the entire season. At all times it contains a very high 

 proportion of cyanophoric glucoside ; the absence of amygdalase and of 



OH 



GTaultherin. Arbutin. 



