J. Iran. Chem. Soc., Vol. 6, No. 2 June 2009, pp.219~229.

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Enzyme Inhibition and Activation: A General Theory

A.A. Saboury*

Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran

The rate of an enzymatic reaction may be changed by a moderator. Usually, the effect is to reduce the rate, and this is called inhibition. Sometimes the rate of enzyme reaction is raised, and this is called activation. Not only enzyme activation is subject of a less detailed presentation, but also enzyme inhibition and activation are very often discussed independently in enzymology. I attempt to introduce a general model of enzyme inhibition and activation to allow one to interpret inhibition and activation from a mechanistic or physical perspective using the significance of cooperativity as a new approach. The magnitude of interaction between substrate and inhibitor binding sites is given by the α parameter and the magnitude of increasing catalytic reaction constant is given by the β parameter, which both parameter values characterize the type of inhibition and activation. The moderation of mushroom tyrosinse is described by application of the model as a typical.

Keywords: Inhibition, Activation, Cooperativity, Enzyme kinetics

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