1907.] Studies on Enzyme Action. 363 



asparagine in experiments with rnaltase prior to the appearance of Ford's 

 communication : finding them to be practically without influence, we felt 

 safe in using them with invertase. As a rule, the activity of invertase is 

 much increased by amino-acids ; the experiments on which we rely were all 

 made in presence of glycine. 



Nature of Enzymes. — Granting that both glucose and fructose inhibit the 

 action of invertase on cane sugar, it would seem to follow that this enzyme 

 is so constituted that it can adapt itself to both sections of the biose. 

 Unfortunately, no satisfactory expression of the structure of cane sugar has 

 been arrived at hitherto, so that we are unable to formulate the changes 

 which the biose undergoes on hydrolysis in a definite manner. It is an 

 altogether peculiar substance, its extraordinary instability in presence of 

 acids being most remarkable in comparison with that of other bioses* from 

 which it does not differ markedly in most respects. 



Invertase, the enzyme correlative with cane sugar, is equally remarkable 

 among enzymes on account of its extreme activity. 



Apparently, cane sugar is a derivative of a-glucose, to judge from 

 O'Sullivan and Tompson's observations ;f nevertheless it is not attacked by 

 rnaltase and as this acts on all the simple a-glucosides, it cannot well belong 

 to their class. Moreover, taking into account Pottevin's statement^ that 

 methyl-fructoside is not hydrolysed by extracts of S. octosporus, Mucor mucedo 

 and Mucor alternans, which hydrolyse cane sugar and maltose, it must be 

 supposed, in like manner, that cane sugar is not a simple fructoside. 



These conclusions are in entire harmony with that derived from the study 

 of inhibiting agents, so that there is little room for doubt that during hydro- 

 lysis the enzyme extends its influence over the whole of the cane sugar 

 molecule — being intimately correlated in all its parts with the carbohydrate 

 in the manner postulated in No. III§ of these communications. 



The question arises whether this is true of other biases. || The experi- 

 mental material is not yet sufficient for the discussion of the problem, 

 but there are already indications which make it probable — at all events, in 

 the case of milk sugar — that what is true of cane sugar and its correlative 

 enzyme applies generally. 



It is commonly assumed that maltose is an a-glucoside, because rnaltase, 

 which hydrolyses it, also acts on simple glucosides such as methyl- 



* Cf. IV, p. 530. 



f Cf. E. F. Armstrong, ' Chem. Soc. Trans./ 1903, vol. 88, p. 1308. 

 X 'An. Inst. Past., 5 3903, vol. 17, p. 43. 

 § Pp. 522—524. 



|| To avoid periphrasis, it appears desirable to term those enzymes which act on simple 

 glucosides monases and those which attack the biose sugars biases. 



