Studies on Enzyme Action. 



371 



The observations we were able to make with several of the Linacece 

 during the season of 1910 were of such interest in connexion with our inquiry 

 into the nature and distribution of enzymes and in other respects also, that 

 we were led to extend the inquiry to the family generally during the past 

 year ; we, therefore, grew all the species we could procure ; this work was 

 carried on simultaneously with that recorded in the two previous communi- 

 cations and that on Lotus corniculatus. 



We propose in future to speak of the specific enzyme corresponding to 

 linamarin as linase, as it appears to be present in so large a number of 

 species of Linacece as to be characteristic of the genus. 



A question of primary importance to be answered was whether the 

 properties deduced from the study of the effects produced by " Phaseoluna- 

 tase " were those characteristic of a single enzyme linase or due to a mixture 

 of enzymes. 



Armstrong and Horton, in agreement with Dunstan and his co-workers, 

 came to the conclusion that the " enzyme " extracted from Phaseolus lunatus 

 is practically without action on amygdalin ; they found, however, that it 

 acted readily on prunasin as well as on linamarin (phaseolunatin). Now that 

 it is established that " emulsin " is a mixture of several enzymes, one of 

 which resolves amygdalin into glucose and prunasin, it is obviously easy to 

 explain the difference between the behaviour of the Phaseolus enzyme and 

 that of emulsin — to realise, in fact, that it is due to the absence of 

 amygdalase from the Phaseolus preparation. But whilst both linamarin 

 and prunasin are hydrolysed by the Phaseolus " enzyme," prunase, the 

 correlate of prunasin — whether it be prepared from the almond or (as shown 

 in the previous communication) from any other source — is without action on 

 linamarin. It is important that the significance of this difference should be 

 fully understood. 



The two glucosides are represented by the following formulae : — 

 CH 3 H 

 CH 3 — C.CN C 6 H 5 — C.CN 



6 o 



OeHnOg C 6 Hii0 5 

 Linamarin. Prunasin. 



The recognition of two distinct enzymes, each corresponding to one of 

 these two compounds, the one (linase) capable of determining the hydrolysis 

 of both glucosides, the other (prunase) limited in its action to the single 

 glucoside to which it corresponds, would be a fact of no slight consequence 

 in connexion with the theory of enzyme action. 



