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Thermodynamics of Enzyme 

 Reactions 



I. Collision Theory of Reactions 



Thermodynamics deals with the gross, macroscopic properties of a 

 system. It can also be related to events on a molecular scale by kinetic 

 theory. This chapter is concerned with the latter aspects of thermo- 

 dynamics as applied to enzyme reactions. As discussed in Chapters 17 

 and 18, most biological reactions are enzymatically controlled. The 

 current chapter may be considered as an application of thermodynamics 

 to molecular biology. Using thermodynamics and kinetic theory, it is 

 possible to relate the energy changes during enzyme reactions to the 

 changes of the reaction rate constants 1 with temperature. Thus, the 

 temperature dependence of the rate constants can be used to find energy 

 changes other than those discussed in the last two sections of the last 

 chapter. Before applying the theory to enzyme reactions, the theory of 

 reactions in general will be developed. Because gas phase reactions are 

 easiest to discuss, they are introduced first. 



The idea of energy changes during a chemical reaction may appear 



1 For a discussion of reaction rate constants, see Chapters 17 and 18. 



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