Studies in the Mechanism of Enzyme Action. 3 



established between their contents and the thermostats, into corresponding 

 tubes of the respective series were introduced in portions of 1 cm.^, solutions 

 of the enzyme, prepared half-hour to one hour previously, containing respec- 

 tively 3'0 mgrm., 475 mgrm., 6"0 mgrm., and 7'0 mgrm. of the enzyme powder 

 per cm.^. The tubes were now closed with selected corks — treated just 

 before use with boiling water from the jet of a wash bottle — and incubated 

 at the temperatures of the thermostats for 16 hours. At the end of this 

 time, the enzyme action was stopped by plunging the tubes for seven minutes 

 into boiling water, the corks having first been withdrawn, and each rapidly 

 washed with 1 cm.-^ of distilled water, the washings being added to the 

 contents of the corresponding tubes. On being cooled to laboratory tem- 

 perature, the contents of each tube were diluted to 50 cm}\ and the 

 percentage of maltose hydrolysed, determined by Bertrand's method,* on 

 20 cm.^ of the diluted mixture. The numbers obtained are set out in the 

 accompanying Table. 



Temperature at beginning 

 and end of each 

 experiment. 



Maltose hydrolysed per cent, with the following 

 enzyme concentrations. 



6 X 10-^ 



9 -5 X lO-*. 



12 X lO^-'. 



14 X 10-*. 



17 -0 







21-1 



28-2 



17 -0-17 -1 





16-9 







17 -7-17 -8 



11 -4 









22 -9-23 -2 









46-4 



24 -7-24 -9 







40 -6 





25 -0-24 -7 





28 -2 







25 -2-25 -4 



21 -1 









32 -0 







65 -2 





32 -1-32 -0 









82 -0 



32 -2-32 -0 





47 -9 







32-2-32 -1 



28 -2 









35 -4 









94-3 



35 o 





52 -5 



75 -1 





37 -0-36 -9 









92 -5 



37 -8-38 -2 



28 -2 









38 -0-38 -3 







71-7 





38 -3-39 





47 -9 







40 -U 



19-7 









42-0 







54-1 



76-8 



42 -0-42 -2 





29-7 







42 -3-42 -2 



11 -4 









45-0 







24-0 



49-4 



45 -2-45 -4 





14-2 







47 -6-47 -2 









24-0 



On plotting as ordinates the jjercentage of maltase hydrolysed, and as 

 aljsciss;e the corresponding mean temperature, these numbers give the 

 graphical representation of fig. 2. 



* 'Bull. Soc. Cliiru.,' (3), vol. 35, p. 1285 (1908). 



B 2 



