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.

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A vitamin B12 solution (hydroxocobalamin) in a multi-dose bottle, with a single dose drawn up into a syringe for injection. Preparations are usually bright red.

Vitamin B12

Water-soluble vitamin involved in metabolism.

Water-soluble vitamin involved in metabolism.

A vitamin B12 solution (hydroxocobalamin) in a multi-dose bottle, with a single dose drawn up into a syringe for injection. Preparations are usually bright red.
A blister pack of 500 µg methylcobalamin tablets
Methylcobalamin (shown) is a form of vitamin B12. Physically it resembles the other forms of vitamin B12, occurring as dark red crystals that freely form cherry-colored transparent solutions in water.
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It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism.

A block of electrolytically refined cobalt (99.9% purity) cut from a large plate

Cobalt

Chemical element with the symbol Co and atomic number 27.

Chemical element with the symbol Co and atomic number 27.

A block of electrolytically refined cobalt (99.9% purity) cut from a large plate
Cobalt(II) chloride hexahydrate
Structure of tetrakis(1-norbornyl)cobalt(IV)
Early Chinese blue and white porcelain, manufactured c. 1335
Cobalt ore
World production trend
Cobalt prices February and March 2021 (USD$ per ton)
Cobalt prices 2016 to 2021 5 years (USD$ per ton)
Cobalt blue glass
Cobalt-colored glass
alt=chemical diagram of cobalamin molecule|Cobalamin
alt=two cobalt-deficient sheep facing away from camera|Cobalt-deficient sheep

Cobalt is the active center of a group of coenzymes called cobalamins.

Sphalerite (ZnS)

Zinc

Chemical element with the symbol Zn and atomic number 30.

Chemical element with the symbol Zn and atomic number 30.

Sphalerite (ZnS)
Zinc acetate
Zinc chloride
Late Roman brass bucket – the Hemmoorer Eimer from Warstade, Germany, second to third century AD
Various alchemical symbols for the element zinc
Andreas Sigismund Marggraf is given credit for first isolating pure zinc
Galvanization was named after Luigi Galvani.
Percentage of zinc output in 2006 by countries
World production trend
Zinc Mine Rosh Pinah, Namibia
Zinc Mine Skorpion, Namibia
Hot-dip handrail galvanized crystalline surface
Cast brass microstructure at magnification 400x
Zinc oxide is used as a white pigment in paints.
Addition of diphenylzinc to an aldehyde
GNC zinc 50 mg tablets. The amount exceeds what is deemed the safe upper limit in the United States (40 mg) and European Union (25 mg)
Zinc gluconate is one compound used for the delivery of zinc as a dietary supplement.
Ribbon diagram of human carbonic anhydrase II, with zinc atom visible in the center
Zinc fingers help read DNA sequences.
Foods and spices containing zinc

Enzymes with a zinc atom in the reactive center are widespread in biochemistry, such as alcohol dehydrogenase in humans.

Folate

One of the B vitamins.

One of the B vitamins.

Chemical structure of the folate family
Biotransformation of folic acid into folinic acids where R = para-aminobenzoate-glutamate.
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In the United States and many other countries, wheat flour is fortified with folic acid; some countries also fortify maize flour and rice.

The exact mechanisms involved in the development of schizophrenia and depression are not entirely clear, but the bioactive folate, methyltetrahydrofolate (5-MTHF), a direct target of methyl donors such as S-adenosyl methionine (SAMe), recycles the inactive dihydrobiopterin (BH2) into tetrahydrobiopterin (BH4), the necessary cofactor in various steps of monoamine synthesis, including that of dopamine.

Methane bubbles can be burned on a wet hand without injury.

Methanogen

Methanogens are microorganisms that produce methane as a metabolic byproduct in hypoxic conditions.

Methanogens are microorganisms that produce methane as a metabolic byproduct in hypoxic conditions.

Methane bubbles can be burned on a wet hand without injury.

Different methanogenic reactions are catalyzed by unique sets of enzymes and coenzymes.

Transketolase

Enzyme that is encoded by the TKT gene.

Enzyme that is encoded by the TKT gene.

Mechanism of fructose-6-phosphate to xylulose-5-phosphate in transketolase active site
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The cofactor necessary for this step to occur is thiamin pyrophosphate (TPP).

Dihydrofolate reductase from E. coli with its two substrates dihydrofolate (right) and NADPH (left), bound in the active site. The protein is shown as a ribbon diagram, with alpha helices in red, beta sheathes in yellow and loops in blue. Generated from 7DFR.

Enzyme kinetics

Study of the rates of enzyme-catalysed chemical reactions.

Study of the rates of enzyme-catalysed chemical reactions.

Dihydrofolate reductase from E. coli with its two substrates dihydrofolate (right) and NADPH (left), bound in the active site. The protein is shown as a ribbon diagram, with alpha helices in red, beta sheathes in yellow and loops in blue. Generated from 7DFR.
As larger amounts of substrate are added to a reaction, the available enzyme binding sites become filled to the limit of V_\max. Beyond this limit the enzyme is saturated with substrate and the reaction rate ceases to increase.
Progress curve for an enzyme reaction. The slope in the initial rate period is the initial rate of reaction v. The Michaelis–Menten equation describes how this slope varies with the concentration of substrate.
Lineweaver–Burk or double-reciprocal plot of kinetic data, showing the significance of the axis intercepts and gradient.
Random-order ternary-complex mechanism for an enzyme reaction. The reaction path is shown as a line and enzyme intermediates containing substrates A and B or products P and Q are written below the line.
Saturation curve for an enzyme reaction showing sigmoid kinetics.
Pre-steady state progress curve, showing the burst phase of an enzyme reaction.
Kinetic scheme for reversible enzyme inhibitors.
The energy variation as a function of reaction coordinate shows the stabilisation of the transition state by an enzyme.

These measurements either use changes in the fluorescence of cofactors during an enzyme's reaction mechanism, or of fluorescent dyes added onto specific sites of the protein to report movements that occur during catalysis.

Archaea

Archaea (singular archaeon ) constitute a domain of single-celled organisms.

Archaea (singular archaeon ) constitute a domain of single-celled organisms.

Archaea were found in volcanic hot springs. Pictured here is Grand Prismatic Spring of Yellowstone National Park.
The ARMAN are a group of archaea recently discovered in acid mine drainage.
Membrane structures. Top, an archaeal phospholipid: 1, isoprene chains; 2, ether linkages; 3, L-glycerol moiety; 4, phosphate group. Middle, a bacterial or eukaryotic phospholipid: 5, fatty acid chains; 6, ester linkages; 7, D-glycerol moiety; 8, phosphate group. Bottom: 9, lipid bilayer of bacteria and eukaryotes; 10, lipid monolayer of some archaea.
Bacteriorhodopsin from Halobacterium salinarum. The retinol cofactor and residues involved in proton transfer are shown as ball-and-stick models.
Sulfolobus infected with the DNA virus STSV1. Bar is 1 micrometer.
Archaea that grow in the hot water of the Morning Glory Hot Spring in Yellowstone National Park produce a bright colour
Methanogenic archaea form a symbiosis with termites.

Methanogenesis involves a range of coenzymes that are unique to these archaea, such as coenzyme M and methanofuran.

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Pyruvate dehydrogenase

Enzyme that catalyzes the reaction of pyruvate and a lipoamide to give the acetylated dihydrolipoamide and carbon dioxide.

Enzyme that catalyzes the reaction of pyruvate and a lipoamide to give the acetylated dihydrolipoamide and carbon dioxide.

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Simplified mechanism for pyruvate dehydrogenase reaction. The TPP coenzyme is shown with abbreviated substituents.
Pyruvate dehydrogenase E1 subunit of E. coli. Colors represent different chains. Structure determined by Arjunan et al. Biochemistry 2002. Created with PyMol.
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The conversion requires the coenzyme thiamine pyrophosphate.

Structure of coenzyme A: 1: 3′-phosphoadenosine. 2: diphosphate, organophosphate anhydride. 3: pantoic acid. 4: β-alanine. 5: cysteamine.

Coenzyme A

Structure of coenzyme A: 1: 3′-phosphoadenosine. 2: diphosphate, organophosphate anhydride. 3: pantoic acid. 4: β-alanine. 5: cysteamine.
Details of the biosynthetic pathway of CoA synthesis from pantothenic acid.
Some of the sources that CoA comes from and uses in the cell.

Coenzyme A (CoA, SHCoA, CoASH) is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle.