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A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst (a catalyst is a substance that increases the rate of a chemical reaction). Cofactors can be considered "helper molecules" that assist in biochemical transformations.
Prosthetic groups are a subset of cofactors. Loosely bound metal ions and coenzymes are still cofactors, but are generally not called prosthetic groups. [2] [3] [4] In enzymes, prosthetic groups are involved in the catalytic mechanism and required for activity. Other prosthetic groups have structural properties.
In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually utilizes NADP+ or NAD+ as cofactors.
Thiamine pyrophosphate (TPP or ThPP), or thiamine diphosphate (ThDP), or cocarboxylase [1] is a thiamine (vitamin B 1) derivative which is produced by the enzyme thiamine diphosphokinase. Thiamine pyrophosphate is a cofactor that is present in all living systems, in which it catalyzes several biochemical reactions.
Pyruvate dehydrogenase deficiency (PDCD) can result from mutations in any of the enzymes or cofactors used to build the complex. Its primary clinical finding is lactic acidosis . [ 18 ] Such PDCD mutations, leading to subsequent deficiencies in NAD and FAD production, hinder oxidative phosphorylation processes that are key in aerobic respiration.
If an enzyme needs coenzyme to work itself, it is called an apoenzyme. In fact, it alone cannot catalyze reactions properly. Only when its cofactor comes in and binds to the active site to form holoenzyme does it work properly. One example of the coenzyme is Flavin. It contains a distinct conjugated isoalloxazine ring system.
Tyrosine hydroxylase or tyrosine 3-monooxygenase is the enzyme responsible for catalyzing the conversion of the amino acid L-tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA). [5] [6] It does so using molecular oxygen (O 2), as well as iron (Fe 2+) and tetrahydrobiopterin as cofactors.
Four key cofactors are required for the reaction catalyzed by the lysine 2,3-aminomutase enzyme. They are: S-Adenosyl methionine (SAM): Helps generate the radical intermediate by borrowing an electron. [5] Pyridoxal phosphate (PLP): Responsible for binding of the amino acid during reaction. The pi-system of this molecule facilitates radical ...