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see coenzymecoenzyme
, any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a particular enzyme or exist freely in solution, but in either case it participates intimately in
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; vitaminvitamin,
group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes.
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(or Vitamin B12), C63H88CoN14O14P, a cobalt-corrin complex in which the cobalt atom is bonded to a cyano group, a nucleotide residue, and four reduced pyrrole rings; molecular weight, 1355.40. Cyanocobalamin is a dark-red crystalline compound, which is soluble in water and polar organic solvents. It was first isolated in crystalline form from cattle liver. Its structure was established by A. Todd and D. Crowfoot Hodgkin and their co-workers.

The primary sources of cyanocobalamin in nature are microorganisms; cyanocobalamin is synthesized by several bacteria, by actinomycetes, and by blue-green algae. It occurs in almost all animal tissues. It is not encountered, as a rule, in the tissues of higher plants (legume tubers are an exception). In ruminants, it is synthesized in sufficient amounts by the microflora of the intestine and the rumen. In man and several higher animals, such as birds and hogs, its synthesis by intestinal microflora is insufficient, and thus the vitamin must be obtained from food. The daily requirement for humans is about 5 μg. The major sources of the vitamin are liver, kidneys, fish meal, and milk.

In the form of its coenzymes methylcobalamin and deoxyadenosylcobalamin, cyanocobalamin participates in the enzymic reactions involved in hematopoiesis and facilitates normal liver function and nerve fiber regeneration. It is produced by microbiological synthesis using propionic-acid bacteria for the fermentation process.

Vitamin B12 is used for the treatment of pernicious anemia and other anemias, as well as of diseases of the central and peripheral nervous systems and the liver. It is prescribed in solutions for intramuscular injections. (See alsoVITAMINS; ANEMIA; and COBALAMINS.)


Smith, L. Vitamin B12. Moscow, 1962. (Translated from English.)
Friedrich, W. Vitamin B12 und Verwandte Corrinoide, 3rd ed. Stuttgart, 1975.



vitamin B12
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We also conducted an open study of 10 patients with well-documented cobalamin deficiency related to PA who received 1000 mcg/d oral crystalline cyanocobalamin for at least 3 months.
The science is young, over the next few years, exciting new research will help determine the relative benefits of highly bioavailable forms of cyanocobalamin and bioactive methylcobalamin.
Calibrators with spectrophotometrically assigned cyanocobalamin concentrations from 0 to 2000 ng/L were prepared in a base of human serum with [B.
4 - 1 mg/day) and monthly intramuscular or subcutaneous administration of cyanocobalamin (100 mcg).
Hydroxocobalamin does not contain a cyanide molecule, and is therefore safer than cyanocobalamin for patients who are sensitive to the deleterious effects of small doses of cyanide.
3 mg Cyanocobalamin (Vitamin B12) mega-dose sub-lingual lozenge, has essentially no risks or adverse side effects to the general population including sedation and drowsiness found in many allergy medications currently available.
In previous research, oral administration of pyridoxine or intramuscular administration of vitamin B12 (in the form of cyanocobalamin or hydroxocobalamin) provided symptomatic relief in patients with diabetic neuropathy.
PreHistin is a sublingual lozenge of Cyanocobalamin that is absorbed through the buccal membrane, allowing direct introduction into the bloodstream.
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