n8 SCIENCE PROGRESS 



These two forms, the a and the /3, will give recognisably 

 different glucose compounds, the a and /3 glucosides, and 

 maltose is such a glucose compound, maltose itself being the 

 a-glucose-glucoside, iso-maltose the /3-glucose-glucoside. 



Translated into terms of this nomenclature, the maltose 

 synthesised in Croft Hill's experiments was the /3-maltose, and 

 it was presumably synthesised through the agency of the maltase 

 present in the yeast extract. 



But if the matter be tested, maltase will be found to be 

 without action upon the /3-maltose, and will only hydrolyse 

 the a-maltose, the substance formed during the hydrolysis of 

 starch. 



This is accepted as a statement of the facts by some writers, 1 

 and it is regarded as marking a distinction between the ordinary 

 catalyst and the behaviour of the enzyme catatyst. 



But such a distinction is so vital, and renders the whole 

 interpretation of enzyme action so uncertain if accepted, that any 

 alternative explanations need serious consideration. Bayliss, 3 

 while pointing out the obvious difficulty that if the enzyme is 

 synthesising a sugar it is incapable of hydrolysing, the equili- 

 brium point of the reaction must be affected, indeed abolished, 

 suggests that another possible explanation is that the synthesis 

 of /3-maltose may have been due to the presence of another 

 enzyme. Yeast extract would certainly contain many enzymes, 

 and in some yeasts Henry and Auld have detected appreciable 

 quantities of emulsin. Emulsin, the enzyme usually associated 

 with the breaking down of the glucoside amygdalin, is capable 

 of attacking /3-glucosides, indeed amygdalin itself is really a 

 /3-glucose-glucoside, from which the emulsin (or the amygdalase 

 portion of it, it is really again a group of enzymes that is included 

 under this name 3 ) splits off one molecule of glucose, leaving the 

 mandelo-nitrite glucoside to be still further broken down. If 

 then the yeast extract contained emulsin, this might be expected, 

 in the presence of excess of glucose, to synthesise the /3-maltose. 



The difficulty in the way of accepting this explanation lies in 

 the fact that it is difficult to explain the preponderance of the /3 

 synthetic compound, bearing in mind the relative preponderance 



1 See for instance, Abderhalden, Physiological Chemistry y Trans. Hall, p. 481 

 (1908). 



3 Bayliss, " The Nature of Enzyme Action," Monographs on Biochemistry. 

 3 For review of recent literature, see Euler, loc. cit., p. 23. 



