Experimental conditions for kinetic studies

When the curvature is appreciable it may be necessary to use curve-fitting to estimate the initial slope accurately. Some methods based on integrated rate equations have been described, but for most purposes it is sufficient to use a generic equation such as a quadratic function to describe the progress curve. If this is done there u e several pitfalls to be avoidoL 

In a few cases the rate may initially increase rather than decrease, and when this occurs one should try to determine the cause, or at least conditions in which it does not happen. No simple model predicts an initial acceleration, and so if it occurs it implies either that more complex analysis will be required or that there is an experimental artefact to be eliminated. An example of the first type of explanation might be a slow conversion of the enzyme into a different and more active state when the assay is initiated this may well be interesting and important and full understanding of the enzyme mechanism may require it to be properly analysed, but this is a detailed topic that is beyond the scope of this chapter. A more trivial explanation might be an assay in which the temperature is inadequately controlled and allowed to increase during the first part of the assay this just needs to be eliminated by more careful experimentation. 

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