ENZYMES AS SYNTHETIC AGENTS 119 



of maltase in the yeast extract which experience of yeast extracts 

 would lead investigators to expect. 



As E. F. Armstrong 1 has also shown that emulsin synthesises 

 the o.-maltose, again the opposite form to the one it attacks, the 

 difficulty is here complete, and needs apparently to be worked 

 out upon the line of these suggestions. But unless the difficul- 

 ties can be traced to impurities in the enzyme preparations it 

 seems that whatever suggestion is made to get over the difficulty 

 must involve a new interpretation of the nature of an enzyme as 

 an organic catalyst. 2 We need not yet give up the hope of 

 seeing the knot unravelled upon the lines of the simpler interpre- 

 tation of enzyme nature, as Bourquelot and Bridel 3 have recently 

 announced the synthesis of /3-methyl-glucoside from an alcoholic 

 solution of glucose by the aid of emulsin — a fact that suggests a 

 normal behaviour for this enzyme at any rate under certain 

 circumstances. In later papers they attribute this synthetic 

 activity to a lactase present in the extract of emulsin. 4 



With this discussion of the present state of our knowledge of 

 the transition from glucose to maltose in vitro we may briefly 

 consider the process in the tissues of the leaf. Here we are at 

 once met with the surprising difficulty that maltase has not been 

 described as usually present in the tissues of the leaf. This is 

 astonishing in view of the nightly conversion of starch into 

 maltose, and presumably the further change of some of the 

 maltose into mono-saccharose sugars, although carbohydrates 

 may apparently leave the leaf as maltose. 5 The absence of 

 reports as to its occurrence may be due to difficulties in the 

 way of extraction. Students working with me have on one or 

 two occasions obtained indications of hydrolysis of maltose 

 when studying the enzymic activity of extracts of dried and 

 powdered leaves, but certainly such activity is often not recog- 

 nisable. The point seems well worthy of further investigation, 

 especially as the curious facts as to the distribution of storage 

 carbohydrates in leaves may possibly find some explanation in 



1 E. F. Armstrong, toe. cit., p. 75 (1st ed.). 



3 For instance, the suggestion of the existence and synthetic activity of anti- 

 enzymes. See Euler, loc. cit., p. 266. 



3 Compte Rendus, 1912, t. 155, p. 319. 



4 See, for instance, Comptes Rendus, 1912, 155, p. 1553. Synthesis of a-glucosides 

 by another enzyme have now also been recorded. See Comptes Rendus, 1913,156, 

 pp. 168, 491 and 1493. 



* See Mangham, Science Progress, New Series, Nos. 18 and 19. 



