Active sites

Active Sites are specific regions on enzymes where substrate molecules bind and undergo a chemical reaction. These sites are crucial for the enzyme's catalytic activity and are often the target of enzyme inhibitors and activators.

Overview

Active sites are typically formed by amino acids that are far apart in the primary sequence but are brought together in the three-dimensional structure of the folded protein. The arrangement of these amino acids creates a very specific binding site that fits one or more substrates precisely.

Structure and Function

The structure of an active site is directly related to its function. The amino acids that form the active site provide the right environment for the substrate to bind and for the reaction to take place. This includes the correct shape for the substrate to fit, the right charge to attract the substrate, and the necessary functional groups to catalyze the reaction.

Catalysis

The active site is where the enzyme catalyzes the chemical reaction. This involves the breaking and forming of chemical bonds, which is facilitated by the functional groups of the amino acids in the active site. The enzyme lowers the activation energy of the reaction, making it proceed faster than it would without the enzyme.

Regulation

Active sites can be regulated by allosteric regulation, where a molecule binds to a site other than the active site, causing a conformational change that affects the active site's function. This can either activate or inhibit the enzyme's activity.

Inhibition

Enzyme inhibitors can bind to the active site, preventing the substrate from binding and thus stopping the reaction. This is known as competitive inhibition. Non-competitive inhibitors bind to a different site, causing a conformational change that makes the active site less effective.

See Also

• Enzyme
• Substrate (chemistry)
• Enzyme inhibitor
• Allosteric regulation