Cobalamins


Also found in: Dictionary, Thesaurus, Medical.

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 ?
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.
ARS scientists are testing various food and supplement samples using CE-ICP-MS to measure the various cobalamins.
Conversely, approximately 75% of plasma cobalamin binds to TCI, (2) a nonspecific R-binder protein similar to gastric R-binder protein ("R" denotes rapid electrophoretic mobility, distinguishable from intrinsic factor).
The cobalt in hydroxocobalamin is in the 3+ state and cobalamin is abbreviated [Cbl.
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.
HC is synthesized in many cells of the body, including leukocytes, and it binds between 80% and 94% of total Cobalamin in plasma (6).
In the commercial assay, the magnetic beads for capturing TC are the same, but cobalamins are determined by RIA.
ROC curves and areas [with 95% confidence intervals (CIs)] were used to estimate diagnostic accuracy for an increase in holo-TC and cobalamin as a diagnostic marker for diagnosing vitamin Blz malabsorption.
Serum cobalamins and cobalamins in the supernatants from the beads were analyzed by a commercial protein-binding assay (Bayer a/s) on Centaur equipment (reference interval, 200-600 pmol/L).
Plasma cobalamins and erythrocyte folate were determined on the ACS:Centaur [TM] Automated Chemiluminescence System (Bayer A/S) by a competitive protein-binding assay (CV <10%).
The central role of transcobalamin in the metabolism of cobalamin has challenged researchers since its discovery in the 1960s (3).