Cyano cobalamin

Alternatively the cobinamide can be synthesized by first carrying out the hydrolysis of either aquo- or cyano-cobalamin followed by alkylation of the reduced cobinamide. 

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

Serum potassium level, which normally ranges from 3.5 5 mEq/L, and serum cyano-cobalamin level, which normally ranges from 200-800 mcg/ml... 

The search for RNAs with new catalytic functions has been aided by the development of a method that rapidly searches pools of random polymers of RNA and extracts those with particular activities SELEX is nothing less than accelerated evolution in a test tube (Box 26-3). It has been used to generate RNA molecules that bind to amino acids, organic dyes, nucleotides, cyano-cobalamin, and other molecules. Researchers have isolated ribozymes that catalyze ester and amide bond formation, Sn2 reactions, metallation of (addition of metal ions to) porphyrins, and carbon-carbon bond formation. The evolution of enzymatic cofactors with nucleotide handles that facilitate their binding to ribozymes might have further expanded the repertoire of chemical processes available to primitive metabolic systems. 

On the other hand, lactamization occurs at C-8 in aqueous alkali. The 7-hydroxyethyl derivative reacts similarly to give a cyclic ether. The reaction does not necessarily require 02 and is inhibited by excess CN". For B12, some ligand dependence was observed, and the order of reactivity is cyano > aqua > alkyl, sulfonato cobalamin (no reaction). In addition, colour changes during the reaction imply participation of the cobalt atom, but the mechanism is not clear (Scheme 93). 

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... 

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