THE ACTION OF AMYLASE ON STAECH 135 



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The Conditions of Action of Amylase. — The study of 

 the conditions under which the characteristic activity of 

 amylase is manifested will serve as an example for the mode 

 of action of enzymes in general ; in many respects the action 

 of the enzyme resembles the activity of a living organism, 

 e.g. :— 



1. Enzymes are destroyed by heat. 



2. They have an optimum temperature of reaction. 



3. They are not exhausted by continuous activity. 



4. They are greatly affected by alterations in the medium 

 in which they act, e.g., by certain antiseptics and poisons. 



The following experiments wiU serve to illustrate the 

 above statements : — 



Experiment. — Two lots of 20 c.c. each of 3 per cent, 

 starch solution are taken ; to one is added 1 c.c. of unboiled 

 inalt extract, to the other 1 c.c. of boiled extract, and the 

 two solutions warmed to 50° C. On testing with iodine 

 and Fehling solution saccharification will be found to have 

 taken place in the case of the solution to which the unboiled 

 extract was added, while no change takes place in the second 

 mixture. 



Experiment. — A number of test-tubes may be taken contain- 

 ing, say, 20 c.c. of 3 per cent, starch solution and 1 c.c. of malt 

 extract, and kept for an equal time at different temperatures, 

 say, the ordinary laboratory temperature, an incubator at 

 20° C. and water-baths at 50° to 80° C. respectively. At 

 the end of, say, ten minutes all the solutions are quickly 

 brought to the boiling-point and titrated with Fehling solution 

 and ferrous sulphocyanate. It will be found that the greatest 

 amount of sugar has been formed at 50° C. By making a 

 larger number of similar trials at different temperatures the 



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