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 ?
Abbreviations A[beta]: Amyloid-[beta] AdoCbl: Adenosylcobalamin BSO: Buthionine sulfoximine Cbl: Cobalamin CNCbl: Cyanocobalamin EAAT3: Excitatory amino acid transporter 3 EGF: Epidermal growth factor GSCbl: Glutathionylcobalamin GSH: The reduced glutathione GSSG: The oxidized glutathione HCY: Homocysteine IGF-1: Insulin-like growth factor 1 MeCbl: Methylcobalamin MS: Methionine synthase NAC: N-Acetylcysteine NRG-1: Neuregulin 1 OHCbl: Hydroxocobalamin PI3K: Phosphatidylinositol 3-kinase PLM: Phospholipid methylation PV+: Parvalbumin-expressing SAM: S-Adenosylmethionine SAH: S-Adenosylhomocysteine S[O.
Characterization of the cobalamins attached to transcobalamin I and transcobalamin II in human plasma.
Spectroscopic studies of nitric oxide (NO) interactions with cobalamins: reaction of NO with superoxocobalamin(III) likely accounts for cobalamin reversal of the biological effects of NO.
Direct assay for cobalamin bound to transcobalamin (holo-trascobalamin) in serum.
ARS scientists are testing various food and supplement samples using CE-ICP-MS to measure the various cobalamins.
The cobalt in hydroxocobalamin is in the 3+ state and cobalamin is abbreviated [Cbl.
12] levels owing to the measurement of nonactive cobalamin analogues.
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].
Based on analyses in cobalamin-deficient patients before and after therapy, Morkbak and colleagues (1) confirm our finding that cobalamin concentrations correlate with haptocorrin (HC; transcobalamin I) (2) but propose that HC concentrations are regulated by cobalamin status rather than being genetically deter mined, which they mistake as my view.
5) 28 MMA, [micro]mol/L 240 (71-563) 38 Cobalamins, pmol/L 188 (81-770) 46 Total TC, pmol/L 1002 (544-1584) 22 HoloTC, pmol/L 53 (24-180) 55 TC saturation, fraction 0.
HoIoTC calibrators (Axis-Shield) were prepared gravimetrically from a stock solution of recombinant holoTC saturated with cobalamins.