Enzymes are mostly proteins that catalyze various biochemical reactions. The catalytic reaction occurs through a specific region of the enzyme called the ‘active site’.
Enzymes are not destroyed after the reaction. They remain unaltered after the product is released.
The substrate (S) binds to the active site of the enzyme (E) and forms an enzyme-substrate (ES) complex.
This transient complex is then converted into an enzyme-product (EP) complex. The EP complex dissociates releasing the product (P) and free enzyme (E).
Since enzymes are generally made up of proteins, they are sensitive to pH and temperature changes. These factors usually result in the destruction of enzymes.