Bio1332 Biochemistry - Lecture Fourteen - Allosteric Enzymes

An inhibitor is any molecule that acts to reduce the rate of an enzymatic reaction. Inhibitors can bind to the enzyme and prevent it from interacting with its substrate, thereby inhibiting the formation of the enzyme-substrate complex. This can occur through various mechanisms, such as blocking the active site of the enzyme or changing its conformation. Inhibitors are important in regulating enzyme activity and can be used as therapeutic agents to target specific enzymes involved in diseases.

Many enzymes are made from more than one protein chain, known as quaternary structure. These chains can be identical or different. In some cases, when a substrate binds to one subunit (chain), it can influence the binding to other subunits. This phenomenon is referred to as cooperativity, or co-operativity, or co operativity. It describes the interaction and communication between the subunits of an enzyme, leading to a coordinated and efficient enzymatic activity.

The average size of an enzyme is typically around 300 amino acids. Enzymes are proteins that catalyze chemical reactions in living organisms, and they are composed of long chains of amino acids. While the size of enzymes can vary, 300 amino acids is a common average length for these biological catalysts.

Allostery is a phenomenon where a chemical molecule binds to an enzyme at a site other than the active site, leading to changes in the enzyme's kinetic properties. This binding can either enhance or inhibit the enzyme's activity, ultimately affecting its function. Allostery is an important mechanism for regulating enzyme activity and is crucial for various biological processes.

An allosteric effector is any molecule that can bind to an enzyme away from the active site, and by doing so change the enzyme's activity for its substrate. These effectors can either increase the rate of reaction (named allosteric activators), or reduce the rate of reaction (named allosteric inhibitors).