116 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



exact optimum temperature for a given enzyme can be 

 determined. 



Experiment. The following experiment was devised by 

 Effront to show the continuous activity of amylase : 200 c.c. of 

 starch paste are mixed with 3 c.c. of malt extract and left for 

 four hours at 30 C. The liquid is now diluted with distilled 

 water to a volume of 300 c.c., 100 c.c. of this mixture is 

 mixed with a further 200 c.c. of starch solution and heated 

 for one hour to 50 C. ; call this solution A. A second 

 100 c.c. of the original mixture is taken and boiled and after- 

 wards added to another 200 c.c. of starch solution, together 

 with 1 c.c. of the original malt extract. This mixture is heated 

 to 50 C. for one hour ; it may be called solution B. 



Upon titration with Fehling solution the two solutions 

 A and B will be found to give practically identical results, 

 which indicates that 100 c.c. of starch mixture will do as 

 much work as 1 c.c. of fresh malt extract, that is, that the 

 amylase is not exhausted by continuous activity. 



Experiment. Three lots of starch solution of 200 c.c. each 

 are taken, to one of them 0'25 gram of potassium or ammonium 

 alum is added, to the second a few drops of strong solution 

 of potash, while the third is left without any addition. To 

 each solution 1 c.c. of malt extract is added and the three 

 solutions are warmed for one hour at 50 C. Upon titra- 

 tion with Fehling solution the greatest action will be 

 found to have taken place in the solution to which the 

 alum has been added, while the action has been practically 

 inhibited by the potash. 



Effront has studied the effect of a number of salts, such as 

 phosphates and acetates and of organic bases, e.g., asparagin, 

 upon the action of amylase and has found that in most cases a 

 considerable acceleration of the action takes place. These 

 results are of special interest in view of the effect of phosphates 

 upon the fermentation brought about by the enzymes of 

 yeast, which has been studied by Harden and his colleagues. 



