Introduction To Enzymes

Enzymes are biological catalysts that accelerate reaction rates without being consumed.  They are typically proteins located in the cytoplasm, inside organelles, and in cell or organelle membranes.

Enzymes may function intracellularly or can be secreted extracellularly. Most enzymes require a specific temperature and pH to operate at peak efficiency.

Substrates are the reactants that specifically bind to active sites, small regions on the enzyme where the reaction occurs. The remaining parts of the enzyme provide structure to the enzyme or interact with other molecules to promote or inhibit the reaction.

Enzymes change their shape to bind their substrates and catalyze the conversion of substrates into products.  After the reaction, the enzyme releases the product and returns to its original conformation, which allows the enzyme to catalyze additional rounds of the reaction.

Some enzymes only function when associated with cofactors, which assist an enzyme-catalyzed reaction. Non-protein molecules such as vitamins, metal ions, or ATP act as cofactors for various enzymes.