ABSTRACT
In sequential mechanisms, two (or more) substrates are bound to the enzyme first, and then react to give the product. Binding can be random, in any possible sequence, or ordered, with a defined sequence of binding events. Two substrate molecules can bind to the enzyme in random order, i.e. binding of A followed by binding of B or binding of B followed by binding of A leads to the same ternary complex EAB. Many enzymes form a ternary complex with two ligands to catalyze their reaction. Examples are found among transferases, such as phosphoryl-, acetyl-, or methyl transferases. In some enzymes, the two substrates have to be bound in a defined order for the reaction to proceed. Ordered or sequential binding occurs when binding of the first substrate induces a conformational change in the enzyme that leads to formation of the binding site for the second substrate.
