Enzyme Kinetics Overview

The rate at which an enzyme catalyzes a reaction is called the enzyme velocity. It is often measured as the amount of product formed per unit time.

Enzymes are biological catalysts that speed up chemical reactions in living organisms by lowering the activation energy required for the reaction to proceed.

The initial phase of an enzyme-catalyzed reaction where the rate of product formation is increasing. It is usually very short, lasting less than a second.

The phase of an enzyme-catalyzed reaction where the rate of product formation is constant and linear with time. It is the phase that is most commonly studied.

The phase of an enzyme-catalyzed reaction where the rate of product formation slows down and eventually plateaus because the substrate is being depleted.

The Michaelis-Menten equation describes the relationship between the enzyme velocity (V) and the substrate concentration ([S]). It is a key equation in enzyme kinetics.

The Michaelis constant (Km) is a measure of the affinity of an enzyme for its substrate. It is the substrate concentration at which the enzyme velocity is half of its maximum value (Vmax).

The maximum velocity (Vmax) of an enzyme is the rate at which the enzyme catalyzes the reaction when the substrate concentration is very high. At Vmax, all enzyme molecules are saturated with substrate.

The rate at which the enzyme-substrate complex (ES) is formed is equal to the rate at which it breaks down. This means the concentration of ES remains constant over time.

The reaction where the product (P) combines with the enzyme (E) to form the ES complex is ignored. This assumption is valid at the beginning of the reaction when the product concentration is low.

The total concentration of enzyme ([E_total]) is the sum of the free enzyme ([E]) and the enzyme-substrate complex ([ES]).

The rate constant for the breakdown of ES into E and P. It represents the efficiency of the enzyme in converting substrate to product.

The Michaelis-Menten constant. It represents the substrate concentration at which the reaction velocity is half of its maximum value. It reflects the affinity of the enzyme for the substrate and the rate of product formation.

The maximum velocity of the enzyme-catalyzed reaction. It is reached when the enzyme is fully saturated with substrate.

A simplified model of enzyme kinetics that assumes a steady-state concentration of the enzyme-substrate complex and ignores the reverse reaction. It is useful for calculating the kinetics of many enzymatic reactions.

A more complex model that accounts for all five rate constants in the enzyme reaction. It provides a more accurate description of enzyme kinetics than the Michaelis-Menten model.