1912.] 



Studies on Enzyme Action. 



365 



during 24 hours, the extent to which hydrolysis had been effected was 

 determined by estimating the amount of hydrogen cyanide liberated from 

 linamarin, amygdalin and prunasin and the amount of glucose liberated 

 from salicin. 



The results recorded in Table I were all obtained in the manner described. 

 They afford opportunity for comment in many directions. 



It was contended in No. XIII of these studies that the glucoside phaseo- 

 lunatin present in Phaseolus lunatics, which is identical with that in flax 

 (linamarin), is not, as Dunstan, Henry and Auld have asserted, an a-glucoside 

 but a /3-glucoside resembling prunasin ; also that the accompanying enzyme 

 phaseolunatase, which there is reason to believe is identical with the 

 linase present in flax, is a /3-enzyme of the emulsin type, though incapable 

 of acting on amygdalin. These conclusions are entirely in accordance with 

 the observations now recorded. 



It should be mentioned that the linamarin we have used was extracted by 

 ourselves from Phaseolus lunatus beans. 



The values given in the first column of the table under linamarin are low 

 with few exceptions, the most striking being that afforded by Lotus 

 corniculatus. As this plant has been fully discussed in a previous com- 

 munication,* little need be said of it now beyond pointing out that it also 

 has a relatively high degree of activity towards prunasin and salicin such 

 as is not met with in other cases ; it is evident that Lotus corniculatus 

 contains more than one /3-enzyme and in view of the results recorded in 

 the communication referred to it will be important to ascertain whether 

 these enzymes vary concomitantly or independently. 



It is open to question whether values below 1 to 2 per cent, are of any 

 significance. It is possible that such small amounts of action — if not mere 

 experimental errors — are due to the presence of small amounts of a cytase ; 

 but the distinctly high values obtained in the case of Vicia cracca and 

 Meclicago sativa are doubtless significant, particularly as there is an obvious 

 tendency towards high values in the case of nearly all the leguminous plants 

 examined. 



Judging from the values in the Amygdalin column, amygdalase — the 

 enzyme by which the first molecule of glucose is removed from amygdalin — is 

 but sparsely distributed and almost confined to seeds in which amygdalin is 

 present. It is in no way certain that the low values in this column represent 

 the activity of amygdalase proper ; indeed, it is specially significant that high 

 values appear in the case of Vicia species, in view of the occurrence of 



* 'Boy. Soc. Proc.,' 1912, B, vol. 84, p. 471. 



2 C 2 



