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Methylcobalamin
Methylcobalamin (mecobalamin, MeCbl, or MeB) is a cobalamin, a form of vitamin B12, vitamin B. It differs from cyanocobalamin in that the cyanide, cyano group at the cobalt is replaced with a methyl group. Methylcobalamin features an octahedral cobalt(III) centre and can be obtained as bright red crystals. From the perspective of coordination chemistry, methylcobalamin is notable as a rare example of a compound that contains metal–alkyl bonds. Nickel–methyl intermediates have been proposed for the final step of methanogenesis. __TOC__ Production Methylcobalamin can be produced in the laboratory by reducing cyanocobalamin with sodium borohydride in alkaline solution, followed by the addition of methyl iodide. Functions This vitamer, along with adenosylcobalamin, is one of two active coenzymes used by vitamin B-dependent enzymes and is the specific vitamin B form used by 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), also known as methionine synthase. Met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin B12
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. One of eight B vitamins, it serves as a vital cofactor (biochemistry), cofactor in DNA synthesis and both fatty acid metabolism, fatty acid and amino acid metabolism. It plays an essential role in the nervous system by supporting myelinogenesis, myelin synthesis and is critical for the maturation of red blood cells in the bone marrow. While animals require B12, plants do not, relying instead on alternative enzymatic pathways. Vitamin B12 is the most chemically complex of all vitamins, and is synthesized exclusively by certain archaea and bacteria. Natural food sources include meat, shellfish, liver, fish, poultry, Egg as food, eggs, and dairy products. It is also added to many breakfast cereals through food fortification and is available in dietary supplement and pharmaceutical forms. Supplements are commonly taken orally but may be administered via intramuscular injection to treat defic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxocobalamin
Hydroxocobalamin, also known as vitamin B12a and hydroxycobalamin, is a vitamin found in food and used as a dietary supplement. As a supplement it is used to treat vitamin B12 deficiency including pernicious anemia. Other uses include treatment for cyanide poisoning, Leber's optic atrophy, and toxic amblyopia. It is given by injection into a muscle or vein, by pill or sublingually. Side effects are generally few. They may include diarrhea, feeling sick, hot flushes, itchiness, low blood potassium, allergic reactions, and high blood pressure. Normal doses are considered safe in pregnancy. No overdosage or toxicity has been reported with this drug. Hydroxocobalamin is the natural form of vitamin B12 and a member of the cobalamin family of compounds. It is found in both raw and cooked beef, together with other cobalamins. Hydroxocobalamin, or another form of vitamin B12, are required for the body to make DNA. Hydroxocobalamin was first isolated in 1949. It is on the World H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanocobalamin
Cyanocobalamin is a form of Vitamin B12, vitamin used to treat and prevent vitamin B12 deficiency, vitamin deficiency except in the presence of cyanide toxicity. The deficiency may occur in pernicious anemia, following gastrectomy, surgical removal of the stomach, with fish tapeworm, or due to bowel cancer. It is used by mouth, by injection into a muscle, or as a nasal spray. Cyanocobalamin is generally well tolerated. Minor side effects may include diarrhea, nausea, upset stomach, and itchiness. Serious side effects may include anaphylaxis, and low blood potassium resulting in heart failure. Use is not recommended in those who are allergic to cobalt or have Leber's disease. No overdosage or toxicity has been reported. It is less preferred than hydroxocobalamin for treating vitamin deficiency because it has a slightly lower bioavailability. Some studies have shown it to possess an antihypotensive effect. Vitamin is an essential nutrient meaning that it cannot be made by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5-methyltetrahydrofolate-homocysteine Methyltransferase
Methionine synthase (MS, MeSe, MTR) is primarily responsible for the regeneration of methionine from homocysteine in most individuals. In humans it is encoded by the ''MTR'' gene (5-methyltetrahydrofolate-homocysteine methyltransferase). Methionine synthase forms part of the S-adenosylmethionine (SAMe) biosynthesis and regeneration cycle, and is the enzyme responsible for linking the cycle to one-carbon metabolism via the folate cycle. There are two primary forms of this enzyme, the Vitamin B12 (cobalamin)-dependent (MetH) and independent (MetE) forms, although minimal core methionine synthases that do not fit cleanly into either category have also been described in some anaerobic bacteria. The two dominant forms of the enzymes appear to be evolutionary independent and rely on considerably different chemical mechanisms. Mammals and other higher eukaryotes express only the cobalamin-dependent form. In contrast, the distribution of the two forms in Archaeplastida (plants and algae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomethylation
Methylation, in the chemical sciences, is the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These terms are commonly used in chemistry, biochemistry, soil science, and biology. In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA processing. ''In vitro'' methylation of tissue samples is also a way to reduce some histological staining artifacts. The reverse of methylation is demethylation. In biology In biological systems, methylation is accomplished by enzymes. Methylation can modify heavy metals and can regulate gene expression, RNA processing, and protein function. It is a key process underlying epigenetics. Sources of methyl groups include S-methylmethionine, methyl folate, methyl B12. Meth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl Group
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many organic compounds. It is a very stable group in most molecules. While the methyl group is usually part of a larger molecule, bonded to the rest of the molecule by a single covalent bond (), it can be found on its own in any of three forms: methanide anion (), methylium cation () or methyl radical (). The anion has eight valence electrons, the radical seven and the cation six. All three forms are highly reactive and rarely observed. Methyl cation, anion, and radical Methyl cation The methylium cation () exists in the gas phase, but is otherwise not encountered. Some compounds are considered to be sources of the cation, and this simplification is used pervasively in organic chemistry. For ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamer
A vitamer () is any of the related forms in which some vitamin occurs. Each vitamer of a particular vitamin is a compound that performs the functions of that vitamin and prevents the symptoms of deficiency of the vitamin. Early research identified vitamins by their ability to cure vitamin-specific deficiency diseases. For example, vitamin B1 was first identified as a substance that prevented and treated beriberi. Subsequent nutrition research has revealed that all vitamers exhibit biological activity against their specific vitamin deficiency, although different vitamers exhibit different potencies against those diseases. A set of vitamers with related biological activity are grouped together by a general name, or ''generic descriptor'', that refers to similar compounds with the same vitamin function. For example, ''vitamin A'' is the generic descriptor for the class of vitamin A vitamers which include retinol, retinal, retinoic acid, and provitamin carotenoids such as beta-caro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MMACHC
Methylmalonic aciduria and homocystinuria type C protein (MMACHC) is a protein that in humans is encoded by the ''MMACHC'' gene. Function The C-terminal region of the product of the MMACHC gene is similar to TonB, a bacterial protein involved in energy transduction for cobalamin uptake. The MMACHC gene product catalyzes the decyanation of cyanocobalamin as well as the dealkylation of alkylcobalamins including methylcobalamin and adenosylcobalamin. This function has also been attributed to cobalamin reductases. The MMACHC gene product and cobalamin reductases enable the interconversion of cyano- and alkylcobalamins. Clinical significance Mutations are associated with combined homocystinuria and methylmalonic acidemia Methylmalonic acidemias, also called methylmalonic acidurias, are a group of inherited metabolic disorders, that prevent the body from properly breaking down proteins and fats. This leads to a buildup of a toxic level of methylmalonic acid in body .... R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
