DHURRIN 259 



hydrolysis is effected by amygdalase, a /3-glucosidase, which, 

 besides occurring in emulsin, is almost always associated with 

 maltase in yeast even when species of Saccharomyces, e.g. 

 S. Ludwigii, contain no maltase. 



The splitting of amygdalin by emulsin involves three dis- 

 tinct scissions : at the point of union between [a) the two 

 glucose residues, [h) the glucose and the benzaldehyde cyan- 

 hydrin, and {c) the benzaldehyde and the hydrocyanic acid. 

 Scissions at the first two points are hydrolyses effected by 

 amygdalase and prunase respectively ; the third is of a different 

 type, whether the separation of the hydrocyanic acid from the 

 benzaldehyde by a third enzyme, hydroxynitrilase, is not 

 known. 



PRUNASIN. PRULAURASIN, AND SAMBUNIGRIN. 



The three glucosides prunasin, prulaurasin, and sambuni- 

 grin occur respectively in the twigs of Primus padus, the 

 leaves of P. laurocerasus, and the fruit of Samhucus niger. 

 They are all isomeric with mandelonitrile glucoside obtained 

 by the partial hydrolysis of amygdalin ; they differ, how- 

 ever, in their optical activities and in the melting-points of 

 their crystals : — 



Sambunigrin has been synthesized by Fischer and Bergmann.* 



DHURRIN. 

 This is a glucoside closely allied to amygdalin, and occurs 

 in the seedlings of Sorghum vulgare, but not in the older 

 plants ; it has the empirical formula C14H17NO7 and yields, 

 on hydrolysis, glucose, hydrocyanic acid, and parahydroxy- 

 benzaldehyde : — 



Ci^H^NO, + H,0 = C«Hi,Oe + HCN + CeH.OHCHO 



Similar glucosides occur in the seedlings of Panicum and 



Zea. 



Dunstan and Henry give the following method for the 



* Fischer and Bergmann: " Ber. deut. chem. Gesells.," 1917, 50, 1047. 



17* 



