Conformation change diffusion controlled substrate binding

Although the kinetics of binding may control the reaction if enzyme complementarity is too good and the mobility of the enzyme is too restricted, this is unlikely to be a general situation. Even if, because of weak binding, the rate of dissociation of an initially formed enzyme-substrate complex was fast, say 10 /sec, there is still plenty of time for conformational changes which may take place in less than 10 ° sec. This is compatible with those enzyme-catalysed reactions where the rate-limiting step is diffusion-controlled encounter of the enzyme and substrate. 

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