Elements of Enzyme Regulation

The myriad of different enzymatic reactions that occur must be regulated for the proper functioning of a living system. This modulation is achieved by the regulation of key enzymes that control metabolic fluxes (Stadtman, 1966 Hammes, 1982). Enzyme regulation is carried out by one of the following strategies. 

Quantity of enzyme The enzyme concentration in cells is regulated at the synthetic level by genetic control, which may occur positively or negatively. Alternatively, the control can be exerted by the specihc degradative pathways. The genetic control of enzyme (protein) synthesis and specific protein degradation will be considered in the Chapters 12 and 13. 

Catalytic activity The regulation of enzyme activities is achieved in two modes, namely switching on-and-off and tuning up-and-down. Covalent modifications of enzymes effectively switches their activities on or off, whereas noncovalent effectors tune enzyme activities up or down by affecting their kinetic parameters. 

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