(N/A) $\rightarrow$ Each enzyme $(E)$ has a substrate $(S)$ binding site in its molecule. The substrate binds with it to form an enzyme-substrate complex $(ES)$. It soon dissociates into its product $(P)$ and an unchanged enzyme,with an intermediate formation of an enzyme-product complex $(EP)$.
$\rightarrow$ The formation of the $ES$ complex is essential for catalysis.
$E + S \rightleftharpoons ES \longrightarrow EP \longrightarrow E + P$
$\rightarrow$ It can be explained in the following steps:
$\rightarrow$ $(1)$ First,the substrate binds to the active site of the enzyme,fitting into the active site.
$\rightarrow$ $(2)$ The binding of the substrate induces the enzyme to alter its shape,fitting more tightly around the substrate.
$\rightarrow$ $(3)$ The active site of the enzyme,now in close proximity to the substrate,breaks the chemical bonds of the substrate,and a new enzyme-product complex is formed.
$\rightarrow$ $(4)$ The enzyme releases the products of the reaction,and the free enzyme is ready to bind to another molecule of the substrate and run through the catalytic cycle once again.