INFLUENCE OF TEMPERATURE UPON ENZYMES 



much from inactivation of the unheated enzyme as in preferential 

 acceleration of the resynthesis of the substrate, thus opposing the 

 reaction which the unheated enzyme accelerates. If this actually 

 occurs then it is evident that a shift in the equilibrium of the reaction : 



Substrate + water ^ products of hydrolysis 



must be brought about by the heated enzyme, of such a nature as to 

 increase the proportion of the substrate in equilibrium with its products. 

 Such a shift of equilibrium would, of course, necessitate a consumption 

 of energy and a corresponding alteration in the material bringing it 

 about, i. e., in the heated enzyme. 



When heated enzymes are allowed to stand in aqueous solution at 

 room-temperatures they may undergo spontaneous Reactivation. This 

 phenomenon has been more especially studied in connection with the 

 Oxidizing Ferments ; but Gramentzki has observed a similar phenomenon 

 in heated solutions of Diastase, Invertase and pancreatic Trypsin. 

 The following are illustrative data obtained with the commercial 

 starch-splitting enzyme Taka-diastase, obtained from Aspergillus 

 oryzGB. The enzyme-solution was heated to 95 and then immediately 

 cooled and allowed to stand at room temperatures. 



REACTIVATION OF HEAT-INACTIVATED TAKA-DIASTASE (GRAMENTZKI). 



Solution tested. Hydrolyzing power. 



Unheated enzyme '. 12.0 



Heated, immediately after cooling 0.6 



Heated, twenty-five minutes after cooljng 4.2 



Heated, seventy-five minutes after cooling 5.5 



Heated, six hours after cooling 8.2 



Heated, five days after cooling 12.0 



The accelerative influence of raising the temperature upon the 

 hydrolysis of the substrate by an enzyme has been frequently investi- 

 gated quantitatively, and it has been found that the relationship 

 between the temperature and the velocity of hydrolysis is that which 

 commonly pertains in chemical reactions. It may be expressed as 

 follows : 



to\ 



f 



-i- = e 2 \ tito 

 V 



where "\ r i" is the velocity of the hydrolysis at the temperature "ti;" 

 "v " is the velocity of hydrolysis at the temperature "to;" "e" is 



the base of the natural or "Napierian" logarithms (2.71828 ) 



and " n" is a constant which is characteristic for the specific reaction, 

 and is expressive of the degree of effect which temperature exerts 

 upon it. The temperature is measured in "absolute" units, that is to 

 say in degrees centigrade above zero plus 273. The relationship 

 only holds good, however, so long as the temperatures employed do not 



