Cofactor (biochemistry)
Information about Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound tightly to an enzyme and is required for catalysis. They can be considered "helper molecules/ions" that assist in biochemical transformations. Certain substances such as water and various abundant ions may be bound tightly by enzymes, but are not considered to be cofactors since they are ubiquitous and rarely limiting.
An enzyme without a cofactor is referred to as an apoenzyme, and the completely active enzyme (in addition to the cofactor) is called a holoenzyme.
Apoenzyme + cofactor <=> Holoenzyme
Metal ions are common cofactors. In nutrition, the list of essential trace elements reflects their role as cofactors. This list includes manganese, iron, cobalt, nickel, copper, zinc, and molybdenum. Other organisms require additional metals, such as vanadium and tungsten. The study of these cofactors falls under the area of bioinorganic chemistry.
Some cofactors undergo chemical changes during the course of a reaction, undergoing reduction or oxidation. Nonetheless, as a catalyst, cofactors return to their original state in the course of the catalytic cycle. They are not consumed. In this respect, cofactors differ from substrates or coenzymes.
In many cases, the cofactor includes both an inorganic and organic component. One diverse set of examples are the heme proteins, which consists of a porphyrin ring coordinated to iron.
Cofactors vary in their location and the tightness of their binding to the host enzyme. When bound tightly to the enzyme, cofactors are called prosthetic groups. Loosely-bound cofactors typically associate in a similar fashion to enzyme substrates. These are better described as coenzymes, which are organic substances that directly participate as substrates in an enzyme reaction. Vitamins can serve as precursors to coenzymes (e.g. vitamins B1, B2, B6, B12, niacin, folic acid) or as coenzymes themselves (e.g. vitamin C).
An enzyme without a cofactor is referred to as an apoenzyme, and the completely active enzyme (in addition to the cofactor) is called a holoenzyme.
Apoenzyme + cofactor <=> Holoenzyme
Metal ions are common cofactors. In nutrition, the list of essential trace elements reflects their role as cofactors. This list includes manganese, iron, cobalt, nickel, copper, zinc, and molybdenum. Other organisms require additional metals, such as vanadium and tungsten. The study of these cofactors falls under the area of bioinorganic chemistry.
Some cofactors undergo chemical changes during the course of a reaction, undergoing reduction or oxidation. Nonetheless, as a catalyst, cofactors return to their original state in the course of the catalytic cycle. They are not consumed. In this respect, cofactors differ from substrates or coenzymes.
In many cases, the cofactor includes both an inorganic and organic component. One diverse set of examples are the heme proteins, which consists of a porphyrin ring coordinated to iron.
Cofactors vary in their location and the tightness of their binding to the host enzyme. When bound tightly to the enzyme, cofactors are called prosthetic groups. Loosely-bound cofactors typically associate in a similar fashion to enzyme substrates. These are better described as coenzymes, which are organic substances that directly participate as substrates in an enzyme reaction. Vitamins can serve as precursors to coenzymes (e.g. vitamins B1, B2, B6, B12, niacin, folic acid) or as coenzymes themselves (e.g. vitamin C).
External links
- Cofactor at eMedicine Dictionary
- MeSH Enzyme+cofactors
Proteins: enzymes | |
|---|---|
| Topics | Active site - Allosteric regulation - Binding site - Catalytically perfect enzyme - Coenzyme - Cofactor - Cooperativity - EC number Enzyme catalysis - Enzyme inhibitor - Enzyme kinetics - Lineweaver-Burk plot - Michaelis-Menten kinetics - List of enzymes |
| Types | EC1 Oxidoreductases/list - EC2 Transferases/list - EC3 Hydrolases/list - EC4 Lyases/list - EC5 Isomerases/list - EC6 Ligases/list |
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Enzymes are proteins that catalyze (i.e. accelerate) chemical reactions.[1] In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, the products.
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catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance called a catalyst, which is itself not consumed by the overall reaction.
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Water is a common chemical substance that is essential to all known forms of life.[1] In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor.
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Enzymes are proteins that catalyze (i.e. accelerate) chemical reactions.[1] In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, the products.
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Enzymes are proteins that catalyze (i.e. accelerate) chemical reactions.[1] In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, the products.
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The Macro Expansion Template Attribute Language complements TAL, providing macros which allow the reuse of code across template files. Both were created for Zope but are used in other Python projects as well.
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ion is an atom or molecule which has lost or gained one or more electrons, making it positively or negatively charged. A negatively charged ion, which has more electrons in its electron shells than it has protons in its nuclei, is known as an anion
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Nutrition is a science that examines the relationship between diet and health. Dietitians are health professionals who specialize in this area of study, and are trained to provide safe, evidence-based dietary advice and interventions.
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micronutrient.
In geochemistry, a trace element is a chemical element whose concentration is less than 1000 ppm or 0.1% of a rock's composition.
The term is used mainly in igneous petrology.
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In geochemistry, a trace element is a chemical element whose concentration is less than 1000 ppm or 0.1% of a rock's composition.
The term is used mainly in igneous petrology.
See also
- Minor element
- Major element
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2, 3
(oxides: acidic, basic or amphoteric
depending on the oxidation state)
Electronegativity 1.55 (Pauling scale)
Ionization energies
(more) 1st: 717.3 kJmol−1
2nd: 1509.
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(oxides: acidic, basic or amphoteric
depending on the oxidation state)
Electronegativity 1.55 (Pauling scale)
Ionization energies
(more) 1st: 717.3 kJmol−1
2nd: 1509.
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3, 4, 6
(amphoteric oxide)
Electronegativity 1.83 (Pauling scale)
Ionization energies
(more) 1st: 762.5 kJmol−1
2nd: 1561.9 kJmol−1
3rd: 2957 kJmol−1
Atomic radius 140 pm
Atomic radius (calc.
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(amphoteric oxide)
Electronegativity 1.83 (Pauling scale)
Ionization energies
(more) 1st: 762.5 kJmol−1
2nd: 1561.9 kJmol−1
3rd: 2957 kJmol−1
Atomic radius 140 pm
Atomic radius (calc.
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2, 3
(amphoteric oxide)
Electronegativity 1.88 (Pauling scale)
Ionization energies
(more) 1st: 760.4 kJmol−1
2nd: 1648 kJmol−1
3rd: 3232 kJmol−1
Atomic radius 135 pm
Atomic radius (calc.
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(amphoteric oxide)
Electronegativity 1.88 (Pauling scale)
Ionization energies
(more) 1st: 760.4 kJmol−1
2nd: 1648 kJmol−1
3rd: 3232 kJmol−1
Atomic radius 135 pm
Atomic radius (calc.
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2, 3
(mildly basic oxide)
Electronegativity 1.91 (Pauling scale)
Ionization energies
(more) 1st: 737.1 kJmol−1
2nd: 1753.0 kJmol−1
3rd: 3395 kJmol−1
Atomic radius 135 pm
Atomic radius (calc.
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(mildly basic oxide)
Electronegativity 1.91 (Pauling scale)
Ionization energies
(more) 1st: 737.1 kJmol−1
2nd: 1753.0 kJmol−1
3rd: 3395 kJmol−1
Atomic radius 135 pm
Atomic radius (calc.
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2, 1
(mildly basic oxide)
Electronegativity 1.90 (Pauling scale)
Ionization energies
(more) 1st: 745.5 kJmol−1
2nd: 1957.9 kJmol−1
3rd: 3666 kJmol−1
Atomic radius 135 pm
Atomic radius (calc.
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(mildly basic oxide)
Electronegativity 1.90 (Pauling scale)
Ionization energies
(more) 1st: 745.5 kJmol−1
2nd: 1957.9 kJmol−1
3rd: 3666 kJmol−1
Atomic radius 135 pm
Atomic radius (calc.
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Zinc (IPA: /ˈzɪŋk/, from German: Zink) is a chemical element in the periodic table that has the symbol Zn and atomic number 30.
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6
(strongly acidic oxide)
Electronegativity 2.16 (scale Pauling)
Ionization energies
(more) 1st: 684.3 kJmol−1
2nd: 1560 kJmol−1
3rd: 2618 kJmol−1
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(strongly acidic oxide)
Electronegativity 2.16 (scale Pauling)
Ionization energies
(more) 1st: 684.3 kJmol−1
2nd: 1560 kJmol−1
3rd: 2618 kJmol−1
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5
(amphoteric oxide)
Electronegativity 1.63 (Pauling scale)
Ionization energies
(more) 1st: 650.9 kJmol−1
2nd: 1414 kJmol−1
3rd: 2830 kJmol−1
Atomic radius 135 pm
Atomic radius (calc.
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(amphoteric oxide)
Electronegativity 1.63 (Pauling scale)
Ionization energies
(more) 1st: 650.9 kJmol−1
2nd: 1414 kJmol−1
3rd: 2830 kJmol−1
Atomic radius 135 pm
Atomic radius (calc.
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6, 5, 4, 3, 2, 1, 0, −1
(mildly acidic oxide)
Electronegativity 2.36 (scale Pauling)
Ionization energies 1st: 770 kJ/mol
2nd: 1700 kJ/mol
Atomic radius 135 pm
Atomic radius (calc.
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(mildly acidic oxide)
Electronegativity 2.36 (scale Pauling)
Ionization energies 1st: 770 kJ/mol
2nd: 1700 kJ/mol
Atomic radius 135 pm
Atomic radius (calc.
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Bioinorganic chemistry is a specialized field that spans the chemistry of metal-containing molecules within biological systems. This field is concerned with the control and use of metal ions in biochemical processes.
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Redox (shorthand for reduction/oxidation reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed.
This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide, or the
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This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide, or the
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Redox (shorthand for reduction/oxidation reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed.
This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide, or the
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This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide, or the
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catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance called a catalyst, which is itself not consumed by the overall reaction.
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In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate(s). The substrate binds with the enzyme's active site, and an enzyme-substrate complex is formed.
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Coenzymes are small organic non-protein molecules that carry chemical groups between enzymes. They are substrates for enzymes and do not usually form a permanent part of the enzymes' structures.
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A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as
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porphyrin is a heterocyclic macrocycle derived from four pyrrole-like subunits interconnected via their α carbon atoms via methine bridges (=CH-). The macrocycle, therefore, is a highly conjugated system, and is consequently deeply coloured—the name porphyrin
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3, 4, 6
(amphoteric oxide)
Electronegativity 1.83 (Pauling scale)
Ionization energies
(more) 1st: 762.5 kJmol−1
2nd: 1561.9 kJmol−1
3rd: 2957 kJmol−1
Atomic radius 140 pm
Atomic radius (calc.
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(amphoteric oxide)
Electronegativity 1.83 (Pauling scale)
Ionization energies
(more) 1st: 762.5 kJmol−1
2nd: 1561.9 kJmol−1
3rd: 2957 kJmol−1
Atomic radius 140 pm
Atomic radius (calc.
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A prosthetic group is a non-protein (non-amino acid) component of a conjugated protein. The prosthetic group may be organic (such as a vitamin, sugar, or lipid) or inorganic (such as a metal ion). Prosthetic groups usually bond covalently to their protein.
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In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate(s). The substrate binds with the enzyme's active site, and an enzyme-substrate complex is formed.
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