Human Biochemistry, Vol. 1 - Murray R. 1993

Structure and Functions of Proteins and Enzymes
Enzymes: Kinetics
Modulators of Enzymatic Activity

The flow of energy and matter (in the form of carbon atoms) during METABOLISM depends on enzyme synthesis and proenzyme activation. However, these processes are irreversible. Like all mammalian Proteins, Enzymes break down into Amino Acids (protein turnover). In bacterial Cells, enzyme activity can be “diluted” due to its distribution among daughter cells produced through successive divisions. Although both mechanisms lead to a decrease in Enzyme Concentration and, consequently, in catalytic activity, these processes are slow and resource-intensive. By analogy, it is as if we were to turn off the light by smashing the bulb, and then, to turn it back on, screwed in a new one. Obviously, it is far more efficient to regulate enzyme activity by simply “switching” it on and off. The catalytic activity of certain Key Enzymes is indeed regulated by low-molecular-weight metabolites (see Ch. 6). Low-molecular-weight modulators that suppress enzymatic activity are called negative modulators, while those that enhance it are called positive modulators. We will discuss them in Chapter 10 and subsequent chapters.

Class="center">References

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Engle P.C. Enzyme Kinetics, Wiley, 1977.

Piszkiwicz D. Kinetics of Chemical and Enzyme-Catalyzed Reactions, Oxford Univ. Press, 1977.

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