359 



Studies on Enzyme Action. XVI. — The Enzymes of Emulsin. 

 (I) Prunase, the Correlate of Prunasin. 

 By H. E. Armstrong, F.R.S., E. F. Armstrong and E. Horton. 



(Received April 3— Read May 16, 1912.) 



{International Catalogue of Scientific Literature. 

 Author's title slip : — D. M. Q. 



D 8014 Emulsin (almond). Presence of prunase in 



The subject has been dealt with previously in Nos. X, XII and XIII of 

 these studies, in all of which the view was advocated that the resolution 

 of amygdalin into two molecules of glucose and one of the cyanhydrol 

 (CN'CHPh'OH) by almond emulsin is effected through the agency of two 

 distinct enzymes — amygdalase and a ft-glucase ; the former being the enzyme 

 by which the amygdalin is resolved into glucose and Fischer's glucoside* and 

 the /3-glucase that by which this glucoside is subsequently resolved into 

 glucose and the cyanhydrol. 



" Emulsin " occurs in the almond fruit and in the fruits of a variety of 

 allied species of plants together with aviygdalin. In continuing our studies, 

 we have directed our attention to plant materials containing the simpler 

 cyanophoric. glucoside derivable from amygdalin, the primary object we had 

 in view being to institute a comparison between the " enzyme " associated 

 with the simpler glucosides and almond- emulsin, not without an expectation 

 that in such cases we should succeed in finding the /S-glucase unaccompanied 

 by amygdalase. 



The use to which we had put leaves of the cherry laurel (Prunus laurocerasus)\ 

 had made this plant of special interest to us ; on this account, we selected it, 

 in the first place, for examination, more particularly because Herissey had 

 obtained from the leaves the cyanophoric compound prulaurasin,| which 

 Caldwell and Courtauld,§ in the course of these studies, have shown 

 to be a mixture of the two stereoisomeric glucosides of the formula 

 (JN""CrIPh — — C 6 Hii0 5 , Fischer's glucoside and sambunigrin, the latter 



_ I Prunase and the specific nature of enzyme action 



D 8012 J v J 



D 1850 Prunasin — hydrolysis by prunase. 

 M 3120 Enzyme of Prunus lauroceraszis.] 



* Fischer, < Ber.,' 1895, vol. 28, p. 1508. 

 + ' Eoy. Soc. Proc.,' B, 1910, vol. 82, p. 588. 

 \ 'Compt. Bend.,' 1905, vol. 141, p. 959. 

 § 'Chem. Soc. Trans.,' 1907, vol. 91, p. 671. 



