Cobalamin vitamin cyano

Marcuard SP, Albemaz L, Khazanie PG Omeprazole therapy causes malabsorption of cyano-cobalamin (vitamin B12). Ann Intern Med 1994 120 211-215. 

Hydroxocobalamin (vitamin another antidote, is a potential alternative to sodium nitrite treatment. It works by binding with cyanide to form nontoxic cyano-cobalamin (vitamin Bj ). Although effective and relatively safe in experimental models, the concentration available in the United States requires large infusion volumes and has a short shelf life due to light instability, and reports of anaphylactoid reactions have limited its use (8,13,21). Further studies using higher concentrations available in European formulations may eventually lead to its use as an outpatient alterative to sodium nitrite treatment in the United States (7,32). Other alternatives currently used or undergoing clinical trials in Europe include cobalt salts, limited by their toxicity, aldehydes, and aminophenol derivatives. These alternative treatments are not currently available in the United States (7). 

Patients with ileal resection commonly develop vitamin Bu deficiency, necessitating therapy with parenteral cyano-cobalamin. 

A perspective report emphasised the key role of the application of pressure in kinetic studies in bringing clarity to understanding the mechanism of substitution reactions of cobalamins.193 The effect of various alkyl substituents in the trans position on the kinetic, thermodynamic and ground-state properties has been studied. Cobalamins featuring in these studies were cyanocobalamin (vitamin Bi2), aquacobalamin and the complex formed when the cyano or water ligand is replaced... 

Cobalt is found in vitamin Bn, its only apparent biological site. The vitamin is a cyano complex, but a methyl or methylene group replaces CN in native enzymes. Vitamin-Bi2 deficiency causes the severe disease of pernicious anemia in humans, which indicates the critical role of cobalt. The most common type of reaction in which cobalamin enzymes participate results in the reciprocal exchange of hydrogen atoms if they are on adjacent carbon atoms, yet not with hydrogen in solvent water ... 

Vitamin Bt2, Radioactive. Radioactive cyano-cobalamin radiocyan ocobalami n. Prepn of Co labelled compound Chalet et al. Science 111, 601 <1950). Properties identical with unlabelled vitamin Bl2, except for the presence of radioactive cobelt. Evaluation of dual-isotope Schilling test for pernicious anemia L. S. Zuckier, L. R. Chervu, J Nucl. Med. 25, 1032 (1984). 

Isolierung von kristalllsiertem Vitamin ("Anti-pernicious anaemia factor", Cyano-cobalamin) aus Leber. 

Description. Vitamin B12 is the largest and most complex of all the vitamins. It is unique among vitamins in that it contains a metal ion, cobalt. For this reason cobalamin is the term used to refer to compounds having B12 activity. Methylcobalamin and 5-deoxyadenosyl cobalamin are the forms of vitamin B12 used in the human body. The form of cobalamin used in most supplements, cyano-cobalamin, is readily converted to 5-deoxyadenosyl and methylcobalamin. 

Other ions and neutral molecules can replace the cyano group in cyanocobalamin. Compounds such as hydroxocobalamin (vitamin Biaa), chloro-cobalamin, cyanatocobalamin, thiocyanatocobalamin, and nitrocobalamin, are known. The microbiological activity of these compounds by the L. lactis and L. leichmannii assays is from 30-100% of the activity of cyanocobalamin, depending upon the assay conditions employed. 

This factor constitutes (Holdsworth, 1955) the bulk of the vitamin B12 in chick cecal contents and feces. It is also present in pig feces, and was isolated from this source by Brown et al. (1955) and his co-workers. On chromatography and ionophoresis it behaves very much like cyano-cobalamin (Fig. 1), but its microbiological properties are clearly different (Table III). Its chemical relationship to the other factors of the vitamin Bu group has not yet been established. 

Cyanocobalamin (Formula 6.17) was isolated in 1948 from Lactobacillus lactis. Due to its stability and availability, it is the form in which the vitamin is used most often. In fact, cyanocobalamin is formed as an artifact in the processing of biological materials. Cobalamins occur naturally as adenosylcobalamin and methylcobalamin, which instead of the cyano group contain a 5 -deoxyadenosyl residue and a methyl group respectively. 

Hutner, Provasoli, and Filfus (22a) and Ford (12a) have shown that the protozoan Ochrotnonaa malkamenaia responds almost specifically to cyano> cobalamin, even when in crude extracts and accompanied by other vitamin B]2-like compounds. 

For samples of biolor ical origin, in which the concentration of the vitamin may be extremely low and which may contain analogues, spectroscopic methods that have greater sensitivity and specificity are necessary and one such method, suitable for concentrations of at least 1 jug of cyano-cobalamin per ml, has been proposed by Rudkin and Taylor and is based on the reaction between cyanocobalamin and cyanide in alkaline solution to form a dicyanide complex. This method is as follows ... 

In certain mixtures with other vitamins, or in natural products such as liver extracts, feeding stuffs, etc., the only reliable assay may be a microbiological one (see page 813). In the first case the preparation of the sample for assay presents no difficulty and simple dilution to the required level is sufficient, but with the natural products the vitamin may be present in complex-bound forms or as hydroxocobalamin, which is relatively unstable to heat. Both problems can be resolved by treating the sample with cyanide, thus assisting the extraction by breaking the complexes and converting all of the cobalamin to the more stable cyano compound. ... 

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