1910.] 



Studies on Enzyme Action. 



355 



during 24 hours, the initial optical rotation was 9°"75 and the final value 9°"78. 

 An experiment was then made in the following manner : — 25 c.c. of a 2M/5 

 solution of methyl-a-giucoside having been measured into each of three 50-e.c. 

 Jena flasks and 20 c.c. of water into one, 10 c.c. into the second but none 

 into the third, 5 c.c. of the phaseolunatase solution was added to the flrst, 

 15 c.c. to the second and 25 c.c. to the third. Three other solutions were 

 prepared in the same way but from a solution of the glucoside only half as strong 

 as that first used. From each of these six mixtures a sample of 10 c.c. was 

 withdrawn immediately after adding the enzyme and transferred to a 50 c.c. 

 measuring-flask containing a drop of a solution of sodium hydroxide to stop 

 the action of the enzyme. All the operations were carried out with the 

 liquids at 25°. The main bulk of the solutions was kept at 25° during 

 1-i days and then at 37° during a further 14 days. At intervals of seven 

 days, of 14 days and of 28 days, a sample measuring 10 c.c. was removed 

 from each solution and the action stopped by soda. Each sample was diluted 

 to 50 c.c. and its reducing power was then determined by the method described 

 by Brown, Morris and Millar (' Chem. Soc. Trans./ 1897, vol. 71, p. 278). The 

 following table gives the weights of copper reduced by 20 c.c. of each of the 

 diluted samples : — 



Concentra- 

 tion of the 

 glucoside. 



Volume of 

 enzyme solu- 

 tion per 100 c.c. 

 of acting 

 liquid. 



Weight (gramme) of copper. 



Initial 

 sample. 



Sample after 

 7 days at 25°. 



Sample after 

 14 days at 25°. 



Sample after 14 

 days at 25° and 14 

 at 37". 



M/5 



10 



0 -0037 



0 -0026 



0 0022 



0 -0012 



Mo 



30 



0-0006 



0-0016 



0-0006 



0-0001 



M 5 



50 



0-0007 



0 -0004 



0 -0001 



0 0004 



M; 10 



10 



0-0026 



0 -0016 



0-0009 



0-0001 



M/10 



30 



0-0010 



0 0006 



0 -0008 



0 -0004 



MylO 



50 



0 0002 



0 -0026 



0-0001 



0 -0001 



As a correction involving the deduction of 0-0035 gramme of copper has 

 to be made in each case, on account of the reduction which takes place when 

 the Fehling's solution alone is carried through the series of operations involved 

 in making the determinations, it is obvious that not the slightest amount of 

 methyl-a-glucoside was hydrolysed. 



It might be urged that the exposure of the enzyme at a temperature of 37° 

 during so long a period as 14 days would be likely to diminish its activity 

 considerably, if not to destroy it ; consequently that the prolongation of 

 the experiments over so long a time proves little or nothing. To decide this 

 point, 5 c.c. was withdrawn from each of the six flasks, each sample being 

 VOL. LXXXII. — B. 2 F 



