Enzyme catalysis

Enzyme Catalysis is a process in which enzymes accelerate, or catalyze, chemical reactions. The molecules at the beginning of the process are called substrates, and the enzyme converts these into different molecules, called products. Almost all metabolic processes in the cell need enzyme catalytic activity to occur at rates fast enough to sustain life.

Mechanism of Enzyme Catalysis

Enzyme catalysis involves the reduction of the activation energy of a reaction, which is achieved by the formation of an enzyme-substrate complex. The enzyme binds to the substrate and forms an enzyme-substrate complex, which then undergoes a reaction to form an enzyme-product complex. This complex then dissociates to release the product and the free enzyme.

Factors Affecting Enzyme Catalysis

Several factors can affect the rate of enzyme catalysis, including temperature, pH, enzyme concentration, substrate concentration, and the presence of any inhibitors or activators.

Temperature

The rate of enzyme catalysis increases with temperature up to a maximum point, the optimum temperature. Beyond this point, the enzyme structure begins to denature, and the rate of reaction decreases.

pH

Each enzyme has an optimum pH at which it is most active. Deviations from this pH reduce the enzyme's activity due to changes in the ionization state of the enzyme and substrate molecules.

Enzyme Concentration

The rate of an enzyme-catalyzed reaction increases with an increase in enzyme concentration, provided the substrate concentration is in excess.

Substrate Concentration

At a constant enzyme concentration, the rate of reaction increases with an increase in substrate concentration up to a point, beyond which the rate of reaction becomes constant.

Inhibitors and Activators

Inhibitors are molecules that bind to enzymes and decrease their activity. Activators are molecules that bind to enzymes and increase their activity.

See Also

• Biochemistry
• Metabolism
• Enzyme Kinetics

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