Active Site of Enzyme

Enzyme molecules contain a special pocket or cleft called the active site. The active site, formed by folding of the protein, contains amino acid side chains that participate in substrate binding and catalysis (Fig. 1). The substrate binds the enzyme noncovalently, forming an enzyme–substrate (ES) complex. Binding is thought to cause a conformational change in the enzyme (induced fit model) that allows catalysis. ES is converted to an enzyme–product (EP) complex that subsequently dissociates to enzyme and product.

Figure 1: Schematic representation of an enzyme with one active site binding a substrate molecule.