1905.] On the Probable Existence of Emulsin in Yeast. 579 
Lotase, which hydrolyses lotusin and appears to be otherwise inactive. 
Gynocardase, which hydrolyses gynocardin. 
Myrosin, which hydrolyses sinigrin (potassium myronate) and sinalbin and 
appears to be otherwise inactive. 
Of these four enzymes it is possible that gynocardase may prove to be 
identical with emulsin,* and assuming this, it is evident that the activity 
of each of the three remaining enzymes is associated with a particular type 
of glucoside; thus lotase reacts with lotusin, which differs from all the 
known cyanogenetic glucosides in having the —CN group attached to the 
sugar residue ; myrosin reacts only with glucosides having the —CNS group 
attached to the non-sugar portion of the molecule, and emulsin decomposes 
elucosides having the —CN group associated with the non-sugar portion of 
the molecule. Power and Gornall have, however, obtained from the seeds 
of Taraktogenos Kurzw, a preparation which is stated to decompose both 
potassium myronate and amygdalin.t This may be due to the simultaneous 
presence in this preparation of two ferments, one of the emulsin and the 
other of the myrosin type. 
It will be seen that the range of activity of the glucosidolytic enzyme of 
yeast coincides with that of emulsin in so far as the nature of the glucosides 
decomposed is concerned. As regards the influence of change of temperature 
on the activity of emulsin scarcely any observations are on record, and it 
was considered worth while to ascertain whether, like the yeast enzyme, 
emulsin ceases to be active at about 70°. It is difficult to secure strictly 
comparable conditions for such experiments, since there is no known 
means whereby equivalent solutions of the two materials can be procured ; 
thus, in some comparative experiments, it was found that 1 ec. of a liquid 
obtained by shaking up 1 gramme of Merck’s emulsin with 100 cc. of 
water when added to 10 cc. of a 10-per-cent. solution of amygdalin in water 
decomposed 85 per cent. of the glucoside in 20 hours, whilst 5 grammes 
of yeast, under the same conditions, decomposed only 6°5 per cent. of the 
amygdalin in the same time, whence it would appear that if the glucosido- 
lytic activity of yeast is due to the presence of emulsin, the specimen of 
yeast used in this instance could have contained only 0°0001 of that 
contained in the specimen of commercial emulsin used. 
It was, however, satisfactorily established that a remarkable diminution 
in the activity of emulsin can be brought about by heating, and that total 
disappearance of activity takes place at about the same temperature as that 
observed in the case of yeast. The results recorded in the following table 
* Power and Lees, ‘ Journ. Chem. Soc.,’ 1905, vol. 87, pp. 354 and 357. 
+t ‘Journ. Chem. Soc.,’ 1904, vol. 83, p. 841. 
VOL, LXXVI.—B, 2k 
