360 



Prof. H. E. Armstrong and others. [Apr. 3, 



being the glucoside characteristic of the common black-fruited elder 

 (Sambucus nigra).* 



Finding that it was impossible to extract an enzyme from the comminuted 

 leaf, we resorted to the expedient of using the finely divided leaf material and 

 found that though this was practically without action on amygdaliu, it 

 readily effected the hydrolysis of Fischer's glucoside. Our conclusion was 

 thus verified that two distinct enzymes are concerned in the hydrolysis of 

 amygdalin and our hope realised that it would be possible, to find one or other 

 enzyme occurring alone. 



It appears to be desirable to assign a distinct name in future to the 

 enzyme in " emulsin " by which the resolution of the simple cyanophoric 

 glucoside is effected ; as it occurs very generally in the various species of 

 Prunus, we propose to term it Prunase ; also it will be convenient to use the 

 name Prunasin in speaking of the glucoside (d-mandelonitrile glucoside) 

 which, hitherto, we have termed Fischer's glucoside. 



Prunasin has been isolated from the leaf of Prunus padus\ and of Prunus 

 serotina.\ The leaf of the laurel, P. laurocerasus, as already mentioned, has 

 afforded Prunasin together with the isomeric sambunigrin. In the case of 

 elder also, sambunigrin is present in the leaf. Amygdalin, apparently, on the 

 other hand, has never been separated from leaves but only from fruit kernels : 

 the allied complex di-glucoside vicianin, which is an arabinose-glucose 

 derivative, also occurs in the seed, not in the leaf.§ 



Apparently, the enzymes are distributed in a corresponding manner, 

 prunase occurring both in leaf and fruit, amygdalase .only in minute 

 proportion at most in the leaf but in large proportion in the seed. A typical 

 series of results illustrating the distribution of the two enzymes in the leaf 

 and seed are given at the head of the table in the next communication 

 (XVII, p. 363). 



We venture to think that the argument put forward in previous communi- 

 cations is now fully justified and that it must be regarded as proved that 

 " almond-emulsin " is a mixture of enyzmes two of which are successively 

 concerned in the resolution of amygdalin. Failure to resolve amygdalin 

 must be considered therefore to be primarily a proof that amygdalase is not 

 present but in no way as an indication that the enzyme is absent which 

 can only come into operation after amygdalase has acted. Evidence of the 

 presence of this latter enzyme is afforded by the resolution of prunasin. 



* Bourquelot and Danjou, ' Compt. Bend.,' 1905, vol. 141, pp. 59 and 598. 



t Herissey, ' Arch. Pharm.,' 1907, vol. 245, p. 641. 



X Power and Moore, ' Chem. Soc. Trans,,' 1909, vol. 95, p. 243. 



§ Bertrand, ' Compt. Bend.,' 1906, vol. 143, pp. 832 and 970. 



