moleculesubstrate

Molecule substrate is a molecule that undergoes a chemical transformation in a reaction. In biology, substrates bind to enzymes at the active site and are converted into products. The concept distinguishes substrates from the enzyme, cofactors, products, and inhibitors.

Substrate specificity describes how an enzyme recognizes particular molecular features, such as functional groups, geometry, and chirality. Kinetic descriptions, notably the Michaelis–Menten framework, relate reaction rate to substrate concentration through parameters like Km and Vmax. Binding can involve induced fit, conformational selection, and, in some cases, allosteric effects which alter activity.

In chemistry and materials science, a substrate can refer to the surface or bulk material on which a chemical reaction occurs or onto which molecules adsorb. On solid catalysts, reactions proceed via adsorption of the substrate, surface transformation, and desorption of products. Substrate inhibition or competition can modulate rates when multiple substrates or inhibitors are present.

Examples span enzymatic reactions, such as amylase acting on starch, and catalytic processes, such as hydrogenation of alkenes on metal surfaces. In computational chemistry, substrates are modeled to predict binding modes, transition states, and reaction pathways. See also substrate specificity, enzyme kinetics, catalysis, adsorption.