1910.] 



Studies on Enzyme Action. 



365 



(1) (3) By mixing 10 c.c. of a 4M/10 solution of Fischer's glucoside with 

 10 c.c. of the yeast juice. 



(2) (4) By mixing 10 c.c. of a 4M/10 solution of phaseolunatin with 

 10 c.c. of the pressed yeast juice. 



Solutions (1) and (2) were kept at 37° (3) and (4) at 25°. The yeast juice 

 was used within 30 minutes of receipt, i.e. within an hour of leaving 

 Dr. Harden's hands. After 23 hours the extent to which hydrolysis had 

 taken place in each case was measured by estimating the hydrogen cyanide 

 liberated. 





Solution (20 c.c.) containing 



Temperature. 



1 "ISOS grammes Fischer's glucoside. 



0 "9886 gramme phaseolunatin. 





Weight hydrolysed. 



Percentage 

 hydrolysed. 



Weight hydrolysed. 



Percentage 

 hydrolysed. 



o 



25 

 37 



0 -0915 

 0 -1682 



7-75 

 14 -25 



0-0049 

 0-0098 



0-5 



1 -0 



Seven days later, two experiments were made (at 37°) to ascertain whether 

 the yeast juice had retained its activity and also to contrast its behaviour 

 towards Fischer's glucoside with that towards amygdalin ; the results are 

 remarkable as showing comparatively slight activity towards the latter, only 

 5 per cent, of amygdalin but 13-5 per cent, of the Fischer's glucoside being 

 changed. The yeast enzyme appears to resemble alraoiid-emulsin in its 

 behaviour towards the Phaseolus glucoside. 



Eosenthaler's observations, as already pointed out, serve to raise the 

 question whetlier there may not be in almond-emulsin an enzyme or enzymes 

 capable of affecting the cyanophoric radicle in amygdalin. (He suggests that 

 both a synthetic and an analytic enzyme are present.) 



The fact that mandelonitrile may be separated as such from amygdalin by 

 the action of sulphuric acid of a certain degree of concentration* would appear 

 to lend support to this contention ; this and other similar nitriles have been 

 shown by Ult^ef to be far more stable compounds than was formerly supposed, 

 so that the production of hydrogen cyanide from amygdalin is not to be set 

 down to the mere spontaneous decomposition of the nitrile when liberated in 

 aqueous solution. 



* Walker and Krieble, ' Chem. See. Trans.,' vol. 95, 1909, p. 1374. 

 t ' Rec. Trav. Chim.,' 1909, vol. 28, pp. 1—23 ; 248—260. 



