Cobalamins


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Cobalamins

 

natural biologically active organic cobalt compounds.

The structural base of the cobalamins is a corrin ring consisting of four pyrrole nuclei in which the nitrogen atoms are bonded to a central cobalt atom. The three most well known cobalamins, which differ in the type of substituent for the cobalt atom, are cyanocobalamin, or vitamin B12, and its coenzymes methylcobalamin and 5’-deoxyadenosylcobalamin. Vitamin B12 is a metabolic product of intestinal flora. In man or animals, avitaminosis B12 develops if the absorption of B12 is impaired for any reason. Cobalamins are deposited in the liver in the form of 5’-deoxyadenosylcobalamin, which takes part in a number of enzymic reactions that are accompanied by intramolecular rearrangements. Methylcobalamin is involved in the biosynthesis of the amino acid methionine, methane, and acetic acid. Vitamin B12 is produced industrially by microbiological synthesis.

References in periodicals archive ?
Williams, "A novel role for vitamin B12: Cobalamins are intracellular antioxidants in vitro," Free Radical Biology and Medicine, vol.
The standard reaction mixture contained 100 mM potassium phosphate, pH 7.2,500 [micro]M homocysteine, 152 [micro]MSAM, 2 mM titanium citrate, 250 [micro]M (6R,S)-5-[[sup.14]C]methyltetrahydrofolate (GE Healthcare), 50 [micro]M of the specified cobalamin, and cell extract in a final volume of 1 mL.
Characterization of the cobalamins attached to transcobalamin I and transcobalamin II in human plasma.
Nitric oxide interaction with cobalamins: biochemical and functional consequences.
Direct assay for cobalamin bound to transcobalamin (holo-trascobalamin) in serum.
This hybrid approach allows scientists to quickly detect and measure levels of specific cobalamins, according to research chemists.
The cobalt in hydroxocobalamin is in the 3+ state and cobalamin is abbreviated [Cbl.sup.III] The vitamin [B.sub.12]-IF complex is absorbed in the terminal ileum.
Ageing is associated with a mild decline of cognitive skills but a severe decline of complex cognitive function may be attributed to extrinsic factors, such as cobalamin deficiency[8].
Statistical associations between cobalamin and HC concentrations require no complicated theories.
Vitamin [B.sub.12] (Cobalamin) circulates in plasma bound to 2 carrier proteins, transcobalamin [(TC).sup.4] and haptocorrin (HC).
In the commercial assay, the magnetic beads for capturing TC are the same, but cobalamins are determined by RIA.