Cofactor (biochemistry)

The succinate dehydrogenase complex showing several cofactors, including flavin, iron–sulfur centers, and heme.
A simple [Fe2S2] cluster containing two iron atoms and two sulfur atoms, coordinated by four protein cysteine residues.
The redox reactions of nicotinamide adenine dinucleotide.

Non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst .

- Cofactor (biochemistry)
The succinate dehydrogenase complex showing several cofactors, including flavin, iron–sulfur centers, and heme.

44 related topics

Alpha
3D structure of a hammerhead ribozyme

Ribozyme

Ribozymes (ribonucleic acid enzymes) are RNA molecules that have the ability to catalyze specific biochemical reactions, including RNA splicing in gene expression, similar to the action of protein enzymes.

Ribozymes (ribonucleic acid enzymes) are RNA molecules that have the ability to catalyze specific biochemical reactions, including RNA splicing in gene expression, similar to the action of protein enzymes.

3D structure of a hammerhead ribozyme
Schematic showing ribozyme cleavage of RNA
Image showing the diversity of ribozyme structures. From left to right: leadzyme, hammerhead ribozyme, twister ribozyme
A ribosome is a biological machine that utilizes a ribozyme to translate RNA into proteins

For example, the functional part of the ribosome, the biological machine that translates RNA into proteins, is fundamentally a ribozyme, composed of RNA tertiary structural motifs that are often coordinated to metal ions such as Mg2+ as cofactors.

4Fe-4S clusters serve as electron-relays in proteins.

Bioinorganic chemistry

Field that examines the role of metals in biology.

Field that examines the role of metals in biology.

4Fe-4S clusters serve as electron-relays in proteins.
Myoglobin is a prominent subject in bioinorganic chemistry, with particular attention to the iron-heme complex that is anchored to the protein.
Structure of FeMoco, the catalytic center of nitrogenase.
Like many antibiotics, monensin-A is an ionophore that tightly bind Na+ (shown in yellow).

These metals are used as protein cofactors and signalling molecules.

Mechanism of pyruvate decarboxylation.

Pyruvate decarboxylase

Enzyme that catalyses the decarboxylation of pyruvic acid to acetaldehyde.

Enzyme that catalyses the decarboxylation of pyruvic acid to acetaldehyde.

Mechanism of pyruvate decarboxylation.

Pyruvate decarboxylase depends on cofactors thiamine pyrophosphate (TPP) and magnesium.

Structure of the polymeric [Ca(H2O)6]2+ center in hydrated calcium chloride, illustrating the high coordination number typical for calcium complexes.

Calcium

Chemical element with the symbol Ca and atomic number 20.

Chemical element with the symbol Ca and atomic number 20.

Structure of the polymeric [Ca(H2O)6]2+ center in hydrated calcium chloride, illustrating the high coordination number typical for calcium complexes.
One of the 'Ain Ghazal Statues, made from lime plaster
Travertine terraces in Pamukkale, Turkey

As electrolytes, calcium ions play a vital role in the physiological and biochemical processes of organisms and cells: in signal transduction pathways where they act as a second messenger; in neurotransmitter release from neurons; in contraction of all muscle cell types; as cofactors in many enzymes; and in fertilization.

Structures and names of common heterocyclic compounds

Biotin

One of the B vitamins.

One of the B vitamins.

Structures and names of common heterocyclic compounds

Biotin is a coenzyme for five carboxylase enzymes, which are involved in the digestion of carbohydrates, synthesis of fatty acids, and gluconeogenesis.

A reaction catalyzed by a reductase enzyme

Dehydrogenase

A reaction catalyzed by a reductase enzyme
Alcohol dehydrogenase oxidizes ethanol, with the help of the electron carrier NAD+, yielding acetaldehyde
Reaction catalyzed by succinate dehydrogenase, note the double bond formed between the two central carbons when two hydrogens are removed
Reaction catalyzed by an oxidase, note the reduction of oxygen as the electron acceptor
Nicotinamide Adenine Dinucleotide
Nicotinamide Adenine Dinucleotide Phosphate
Flavin Adenine Dinucleotide
The mechanism of an aldehyde dehydrogenase, note the use of NAD+ as an electron acceptor.

A dehydrogenase is an enzyme belonging to the group of oxidoreductases that oxidizes a substrate by reducing an electron acceptor, usually NAD+/NADP+ or a flavin coenzyme such as FAD or FMN.

Conjugated protein - hemoglobin: 4 subunits are in different colours

Prosthetic group

Non-amino acid component that is part of the structure of the heteroproteins or conjugated proteins, being tightly linked to the apoprotein.

Non-amino acid component that is part of the structure of the heteroproteins or conjugated proteins, being tightly linked to the apoprotein.

Conjugated protein - hemoglobin: 4 subunits are in different colours

Not to be confused with the cofactor that binds to the enzyme apoenzyme (either a holoprotein or heteroprotein) by non-covalent binding a non-protein (non-amino acid)

The 18-electron cycle of porphin, the parent structure of porphyrin, highlighted. (Several other choices of atoms, through the pyrrole nitrogens, for example, also give 18-electron cycles.)

Porphyrin

Porphyrins are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−).

Porphyrins are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−).

The 18-electron cycle of porphin, the parent structure of porphyrin, highlighted. (Several other choices of atoms, through the pyrrole nitrogens, for example, also give 18-electron cycles.)
Porphycene, first porphyrin isomer, synthesised from bipyrrole dialdehyde through McMurry coupling reaction
Various reported Isomers of porphyrin
Heme B biosynthesis pathway and its modulators. Major enzyme deficiences are also shown.
Brilliant crystals of meso-tetratolylporphyrin, prepared from 4-methylbenzaldehyde and pyrrole in refluxing propionic acid
On a gold surface porphyrin derivative molecules (a) form chains and clusters (b). Each cluster in (c,d) contains 4 or 5 molecules in the core and 8 or 10 molecules in the outer shells (STM images).
An example of porphyrins involved in host–guest chemistry. Here, a four-porphyrin–zinc complex hosts a porphyrin guest.
Porphin is the simplest porphyrin, a rare compound of theoretical interest.
Derivatives of protoporphyrin IX are common in nature, the precursor to hemes.
Octaethylporphyrin (H{{sub|2}}OEP) is a synthetic analogue of protoporphyrin IX. Unlike the natural porphyrin ligands, OEP{{sup|2−}} is highly symmetrical.
Lewis structure for meso-tetraphenylporphyrin
Simplified view of heme, a complex of a protoporphyrin IX.
UV–vis readout for meso-tetraphenylporphyrin
Light-activated porphyrin. Monatomic oxygen. Cellular aging

One of the best-known families of porphyrin complexes is heme, the pigment in red blood cells, a cofactor of the protein hemoglobin.

Euler-Chelpin, May 1934

Hans von Euler-Chelpin

German-born Swedish biochemist.

German-born Swedish biochemist.

Euler-Chelpin, May 1934

Harden discovered that the enzyme zymase, discovered by Eduard Buchner, only produces fermentation in interaction with the coenzyme cozymase.

Nitric oxide synthase

Nitric oxide synthases (NOSs) are a family of enzymes catalyzing the production of nitric oxide (NO) from L-arginine.

Nitric oxide synthases (NOSs) are a family of enzymes catalyzing the production of nitric oxide (NO) from L-arginine.

NOSs are unusual in that they require five cofactors.