In: Anatomy and Physiology
Enzymes are bio-catalyst which interacts with a substrate and catalyzes a chemical reaction to form a product, without itself undergoing any change.
An enzyme interacts with a substrate at the active site of the enzyme. Active site: an active site is that site in an enzyme where a substrate comes and attaches itself forming Enzyme-substrate complex and a chemical reaction is carried out.
Whenever a suitable substrate comes in the vicinity of an enzyme,it comes and attaches at the active site of enzyme.There are two theories which explain the interaction of a substrate and an enzyme:
After the reaction is catalyzed, a product-enzyme complex is formed and product is released. Enzyme is ready to be used again.