502 



Dr. E. F. Armstrong. 



[Apr. 5, 



Similar results were obtained by Horace Brown and Glendinning* 

 in the case of the hydrolysis of starch under the influence of diastase. 

 Stress was laid by these observers on the fact that, at first, equal 

 amounts of starch are hydrolysed in equal intervals of time and that 

 subsequently the change follows the usual logarithmic law. 



It is noteworthy, however, that when this logarithmic law is applied 

 either to Henri's results or to those of Adrian Brown for invertase 

 or to those of Horace Brown and Glendinning for diastase, reckoning 

 from the commencement of the change, a series of increasing values is 

 obtained for K, whereas when Henri's equation is used Ki is a constant 

 in each case. It would thus appear that the action of the two enzymes 

 follows the same fundamental law. 



The nature of the change effected by enzymes has been fully 

 discussed by Horace Brown and Glendinning. Starting from the 

 conception that hydrolysis is preceded by a combination of the 

 hydrolyte with the enzyme, on the assumption that the concentration 

 of the added enzyme is very small in relation to the initial concentration 

 of the sugar, they point out that, in the earlier stages of the hydrolysis, 

 the amount of sugar in unit volume will be very large compared with 

 the amount of the combination of sugar with enzyme : consequently, 

 so long as the concentration of the unaltered sugar remains very large 

 compared with that of the combination, this latter will remain almost 

 constant in amount and equal amounts of sugar will be hydrolysed in 

 equal times : the time curve will, in fact, be approximately a straight 

 line. When, however, the amount of sugar present is materially 

 reduced, the combination will more nearly follow the ordinary law of 

 mass action. They point out that this explanation is in accord with all 

 the known facts. 



A considerable body of evidence is put forward in this communication 

 which, in the main, confirms the conclusion arrived at by Horace Brown 

 and Glendinning ; but it will be shown that it is necessary somewhat to 

 extend their argument. 



A novel conception was introduced by Croft Hill in 1898,f who 

 studied the action of maltase on maltose advisedly from the point of 

 view that the change might be reversible. He not only showed that 

 the product of hydrolysis (glucose) exercised a marked retarding effect 

 but also that a change was producible in the concentrated solutions of 

 glucose by maltase ; in his opinion, this retardation was due to reversion 

 and he suggested that maltose was reproduced. Subsequently, in 1 903, J 

 while upholding the view that the change was a reversible one, he came 

 to the conclusion that the main product, at all events, was an isomeride 



* 1 Chem. Soc. Trans.,' .1.902, vol. 81, p. 388. 

 f ' Chem. Soc. Trans.,' vol. 73, p. 634. 

 X 1 Chem. Soc. Trans.,' vol. 83, p. 578. 



