Feb. is, 1921 



Amylase of Rhizopus tritici 



769 



enzyms. Kellerman (17) found that the alkalies without exception 

 seemed to be detrimental and the metals generally injurious to the action 

 of Taka diastase. From the results obtained by these and other investi- 

 gations it is evident that many substances influence the rate of action of 

 the enzym. The data shown here are the results of a single experiment. 

 Four flasks marked a,b,c,d were prepared, each to contain 0.25 gm. of 

 powdered mycelium. A second lot of flasks was prepared, and into flask 

 a were added 100 cc. of a 0.5 per cent starch paste solution; into flask b 

 125 cc. of a 0.5 per cent starch paste and 0.625 gm. glucose; into flask c 

 125 cc. of a 0.5 per cent starch paste and 2.5 gm. glucose; into flask d 

 125 cc of a 0.5 per cent starch paste and 6.25 gm. glucose. After thor- 

 ough mixing, 25 cc. were drawn from flasks b, c, and d, and the reducing 

 sugars were determined volumetrically. The contents of flasksb,c,andd 

 were then poured into the corresponding flasks containing mycelium 

 and digested for 18 hours at 40 C, with the results given in Table V. 

 Table V.— Amount of reducing sugars before and after hydrolysis 

 [Expressed in milligrams per 10 cc. of solution] 



It seems evident from the results of a single test that the presence of 

 glucose decreases the activity of the amylase, since the total reducing 

 sugars formed in sample a is considerably greater than in samples b, c, 

 and d On the other hand, the closely agreeing results of b, c, and d 

 indicate that the amount of glucose present at the strength used in this 

 experiment has no effect upon the hydrolysis of the starch. 



RELATION OF QUANTITY OF STARCH PRESENT TO AMOUNT OF HYDROLYSIS 



This subject naturally involves a consideration of the law of "mass 

 action " and in the literature on this subject there appears to be no 

 agreement of opinion on the question. The investigations show that so 

 far as enzyms are concerned so many factors influence the reaction that 

 no definite conclusion can be drawn. For example, Brown and Glen- 

 dinning (4) showed that when the concentration of the enzym relative 

 to the starch in the early stages is very small, the amount of starch 

 hydrolyzed per unit volume will be very large compared with the amount 

 of the combination of starch and enzym. If the concentration of he 

 unchanged substrate remains very large in relation to that of the 



