Allosteric enzyme
Allosteric enzyme
Allosteric enzyme (/əˌlɒstəˈrɪk ˈɛnzaɪm/; from the Greek allos, "other", and stereos, "solid") is a type of enzyme that changes its conformational ensemble upon binding of an effector, resulting in an apparent change in binding affinity at a different ligand binding site.
Etymology
The term "allosteric" comes from the Greek words allos meaning "other" and stereos meaning "solid". This refers to the fact that allosteric enzymes have multiple binding sites, and binding at one site can affect the enzyme's activity at another site.
Function
Allosteric enzymes are crucial in cellular regulation, as they can increase or decrease their activity in response to molecular signals. This allows the cell to adapt to changes in its environment and maintain homeostasis. Allosteric enzymes work by having separate active sites and allosteric sites. When an effector molecule binds to the allosteric site, it changes the enzyme's shape, which can either enhance or inhibit the enzyme's activity at the active site.
Examples
Examples of allosteric enzymes include hemoglobin, which transports oxygen in the blood and is regulated by oxygen, carbon dioxide, and pH levels, and phosphofructokinase, which is a key enzyme in glycolysis and is regulated by levels of ATP and fructose 2,6-bisphosphate.
Related Terms
- Active site: The part of an enzyme where substrates bind and undergo a chemical reaction.
- Allosteric site: A site on an allosteric enzyme that allows molecules to either activate or inhibit enzyme function.
- Effector: A molecule that binds to a protein and alters the protein's function.
- Enzyme: A protein that acts as a biological catalyst to speed up a chemical reaction.
- Homeostasis: The state of steady internal conditions maintained by living things.
External links
- Medical encyclopedia article on Allosteric enzyme
- Wikipedia's article - Allosteric enzyme
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