ENZYME KINETICS 



that there was a gradual change in slope rather than a sharp 

 break. 



Closing 



Much of the enzyme kinetic data in the literature has been 

 obtained under conditions that make a simple quantitative inter- 

 pretation extremely difficult. As a hypothetical example, a reac- 

 tion involving a coenzyme and a metal ion activator might be 

 studied under conditions where the concentration of one sub- 

 strate was so high as to cause inhibition, the metal ion was par- 

 tially complexed with the anion of the buffer, and the coenzyme 

 was a mixture of ionized forms at the j&H of the medium. It is 

 evident that the details of the mechanism of a reaction of this 

 type would have to be unraveled in the same slow careful way as a 

 snarled fishline. Much is to be gained by isolating effects in 

 their simplest possible form so that experimental results may be 

 expressed mathematically and related to the properties of simpler 

 reactions. 



The interpretation of enzyme kinetic data is subject to a 

 number of pitfalls, but these pitfalls are becoming better under- 

 stood and danger signals are being posted at the dangerous 

 points. Since more than one mechanism may represent a given 

 set of experimental data, anyone who claims that some mecha- 

 nism is the only one possible for a given reaction is skating on ex- 

 tremely thin ice. However, the fact that the discovery of enzy- 

 matic mechanisms is difficult does not diminish interest in them. 

 As we look back on the naivete of early work in enzyme kinetics 

 surely it is reasonable to assume that the data presently available 

 will be subject to reinterpretation in the future. 



When the information presently available on enzyme ki- 

 netics is compared with the vast field of potential application, it 

 is true to say that the surface has just been scratched. In the 

 future we may expect that more of the findings of physical chem- 

 istry and organic chemistry will find application to the study of 

 enzyme kinetics. There are already indications of the basic 



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