44 INFLUENCE OF TEMPERATURE ON BIOLOGICAL SYSTEMS 



apparatus (14, 15), although the values are lower than the estimate of 

 Ludwig and Kuby (17). Temperature variation has a surprising large ef- 

 fect upon the value of ki and it is not at all certain, due to the limitations 

 in the validity of equation 5, that this temperature variation can be truly 

 attributed to the combination of oxygen with cytochrome a.s , since other 

 data have already pointed to the existence of intermediates between cyto- 

 chrome as and oxygen. Thus this large heat of activation could be at- 

 tributed to such steps. 



SUMMARY 



Three approaches to the problem of the determination of the effect of 

 temperature ujion the speed of enzymatic reactions have been briefly out- 

 lined. Of these three, the direct determination of these velocity constants 

 by means of the rapid flow method is by far the best, but, by means of a 

 simple equation, based on the steady state reaction kinetics of the inter- 

 mediate compound, many advantages of the direct method have been 

 retained without the need for the measurement of very short times by the 

 rapid flow apparatus. 



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