Enzymes are biological polymers produced by living organisms that catalyze biochemical reactions. They are crucial for metabolic processes and other chemical reactions in the cell, and are necessary for sustaining the life of organisms. Enzymes are catalysts, so they do not directly involve in biological reactions but help with their efficient occurrence. Enzymes are proteinaceous molecules that possess secondary and tertiary structures, and when they are present in their tertiary structure, their protein chains get folded upon themselves, forming active sites that are responsible for the mechanism of enzyme action and catalysis.

The mechanism of enzyme action involves the following steps:

• An enzyme attracts substrates to its active site.
• The substrates bind to the active site of the enzyme.
• The enzyme catalyzes the chemical reaction by which products are formed.
• The products dissociate from the enzyme surface, releasing the enzyme.
• The enzyme, unchanged by the reaction, is able to react with additional substrate molecules in this manner many times per second to form products.

Enzymes accelerate the rates of chemical reactions without themselves being consumed or permanently altered by the reaction. They increase reaction rates without altering the chemical equilibrium between reactants and products. The catalytic groups at the active site of an enzyme act 10^6 to 10^9 times more effectively than do analogous groups in a nonenzymatic reaction. The reason for the great efficiency of enzymes is not completely understood, but it results in part from the precise positioning of the substrates and the catalytic groups at the active site, which serves to increase the probability of collision between the reacting atoms. In addition, the environment at the active site may be favorable for reaction, such as acidic and basic groups acting together more effectively there, or some strain may be induced in the substrate molecules so that their bonds are broken more easily, or the orientation of the reacting substrates may be optimal at the active site.