

194 Studies on Enzyme Action. 



On comparing the results recorded in the above tables with those 

 given on pp. 190 191, representing the action of acid, it is obvious that 

 the enzyme was much more active than the acid. About 40 per cent. 

 of the glucoside was changed in 5 hours at 22 by the enzyme ; whereas, 

 when acid was used, even in so large a proportion as three molecules 

 of hydrogen chloride to one of glucoside, the same amount of change 

 was effected in only about 20 hours at 75. As the enzymes are 

 undoubtedly of high molecular weight and the proportion of maltase 

 in the yeast extract is certainly small, it would seem to follow that the 

 relative molecular activity of the enzyme is very great compared with 

 that of the acid. But, as pointed out in an earlier paper,* inasmuch 

 as only a small proportion of the acid is actually active, it is probable 

 that the enzyme owes its apparent activity to its greater affinity for 

 the sugar and that, in reality, the acid has the greater hydrolytic 

 activity. 



On account of the rapid alteration in the values of K, it is difficult 

 to make any exact numerical comparison between maltose and methyl 

 glucoside. The initial value of K, in the case of the glucoside, may be 

 estimated at about 0*025 ; in view of the results previously obtained,! 

 which throw considerable light on the behaviour of maltose during the 

 early stages of hydrolysis, the corresponding value for this sugar may 

 be set at 0'12 or even higher. Comparing these initial rates, it would 

 appear that maltose is hydrolysed from five to six times as rapidly as 

 a-methyl glucoside, a result of the same order as that deduced in com- 

 paring the action of chlorhydric acid on the two hexosides. 



Taking into account both the superior stability of the methyl 

 glucoside and the greater influence exercised by the products of 

 change in the case of maltose, the difference in the behaviour of the 

 two compounds on hydrolysis seems to be satisfactorily accounted for. 



* Part 4, loc. cit. 



t ' Koy. Soc. Proc.,' yol. 73, p. 508. 



