WordNet

the 2nd letter of the Roman alphabet (同)b
the blood group whose red cells carry the B antigen (同)type_B, group B
the univalent radical CH3- derived from methane (同)methyl_group, methyl radical

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black(鉛筆の軟度を示す;硬度は『H』(=hard)で表す) / boronの化学記号

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/02/01 17:33:52」(JST)

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Methylcobalamin (mecobalamin, MeCbl, or MeB₁₂) is a cobalamin used in the treatment of peripheral neuropathy, diabetic neuropathy, and as a preliminary treatment for amyotrophic lateral sclerosis. It is a form of vitamin B₁₂ and differs from cyanocobalamin in that the cyanide is replaced by a methyl group.^[1] Methylcobalamin features an octahedral cobalt(III) centre. Methylcobalamin can be obtained as bright red crystals.^[2]

From the perspective of coordination chemistry, methylcobalamin is notable as a rare example of an enzyme that contains metal-alkyl bonds. Nickel-methyl intermediates have been proposed for the final step of methanogenesis.

Production

Methylcobalamin physically resembles the other forms of vitamin B₁₂, occuring as dark red crystals that freely form cherry-colored transparent solutions in water.

Methylcobalamin can be produced in the laboratory by reducing cyanocobalamin with sodium borohydride in alkaline solution, followed by the addition of methyl iodide.^[2]

Functions

This vitamer is one of two active coenzymes used by vitamin B₁₂-dependent enzymes and is the specific vitamin B₁₂ form used by 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), also known as methionine synthase. In physiological terms, it is equivalent to vitamin B₁₂, e.g. for addressing pathologies arising from a lack of vitamin B₁₂, such as pernicious anemia.

Methylcobalamin participates in the Wood-Ljungdahl pathway, which is a pathway by which some organisms utilize carbon dioxide as their source of organic compounds. In this pathway, methylcobalamin provides the methyl group that couples to carbon monoxide (derived from CO₂) to afford acetyl-CoA. Acetyl-CoA is a derivative of acetic acid that is converted to more complex molecules as required by the organism.^[3]

Methylcobalamin is produced by some bacteria. It plays an important role in the environment. In the environment, it is responsible for the biomethylation of certain heavy metals. For example, the highly toxic methylmercury is produced by the action of methylcobalamin.^[4] In this role, methylcobalamin serves as a source "CH₃⁺".

References

^ L. R. McDowell, Vitamins in animal and human nutrition, http://books.google.co.uk/books?id=dXOPBMYIPcQC&pg=PA526
^ ^a ^b David Dophin. Preparation of the Reduced Forms of Vitamin B₁₂ and of Some Analogs of the Vitamin B₁₂ Coenzyme Containing a Cobalt-Carbon Bond. D.B. McCormick and L.D. Wright, Eds. 1971;Vol. XVIII:34-54.
^ 1. J. C. Fontecilla-Camps, P. Amara, C. Cavazza, Y. Nicolet and A. Volbeda, "Structure-function relationships of anaerobic gas-processing metalloenzymes", Nature 2009, volume 460, p. 814-822.doi:10.1038/nature08299
^ Zenon Schneider, Andrzej Stroiński, Comprehensive B12: Chemistry, Biochemistry, Nutrition, Ecology, Medicine, http://books.google.co.uk/books?id=OBlxCKbYCx8C&pg=PA32

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UpToDate Contents

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1. ビタミンB12および葉酸欠乏症の病因および臨床症状 etiology and clinical manifestations of vitamin b12 and folate deficiency
2. ビタミンB12および葉酸欠乏症の生理学 physiology of vitamin b12 and folate deficiency
3. ビタミンB12および葉酸欠乏症の診断および治療 diagnosis and treatment of vitamin b12 and folate deficiency
4. 小児における後天性末梢性ニューロパチーの概要 overview of acquired peripheral neuropathies in children
5. Healthcare for adult immigrants and refugees

English Journal

Pilot study of the effect of methyl B12 treatment on behavioral and biomarker measures in children with autism.

Bertoglio K, Jill James S, Deprey L, Brule N, Hendren RL.SourceDepartment of Psychiatry and Behavioral Sciences, University of California, Davis Medical Center, Sacramento, CA, USA.
Journal of alternative and complementary medicine (New York, N.Y.).J Altern Complement Med.2010 May;16(5):555-60.
OBJECTIVES: The study objectives were to determine whether methyl B12 treatment improves behavioral measures in children with autism and whether improvement is associated with increased plasma concentrations of glutathione (GSH) and an increased redox ratio of reduced glutathione to oxidized glutath
PMID 20804367

Japanese Journal

絞扼性神経障害に対するmethyl B_<12> one shot静注の短期的効果

佐々木正造,原弘明,倉橋豊,堀内静夫,山口智
日本手の外科学会雑誌 = The Journal of Japanese Society for Surgery of the Hand 12(3), 399-403, 1995-11-30
NAID 10008578017

Related Pictures

Methyl B12 5000 mcg Country Life 60 تا می توانید ب 12 مصرف vitamin b12 vitamin b12 cyanocobalamin Methyl B12 5,000 mcg vitamin b12 vitamin b12 methylcobalamin Methyl B12 1000 MCG - Lemon (100 Lozenges Jarrow Formulas, Methyl B-12, Cherry Methyl B12 - Green Healing Wellness

★リンクテーブル★

リンク元	「メチルコバラミン」
関連記事	「B」

「メチルコバラミン」

Methylcobalamin
Systematic (IUPAC) name
	carbanide; cobalt(3+);
Clinical data
AHFS/Drugs.com	International Drug Names
Pregnancy cat.	?
Legal status	?
Routes	oral,sublingual,injection.
Identifiers
CAS number	13422-55-4
ATC code	B03BA05
PubChem	CID 6436232
UNII	BR1SN1JS2W
ChEMBL	CHEMBL1697757
Chemical data
Formula	C63H91CoN13O14P
Mol. mass	1344.40 g/mol
(what is this?) (verify);

　　[★]

英: methylcobalamin MeCbl
同: メチルB12 methyl-B12 MeB12
関: ビタミンB12

ビタミンB12活性体の一種

「B」

　　[★]

気管分岐部下緑
補体のalternative pathwayに関わる蛋白質

Mg2+存在下でC3, B, Dが反応してC3bBbとなり、これがC3転換酵素(C3bBb)あるいはC5転換酵素(C3bBb3b)を形成する。これらはP(properdin)と結合して活性化し、それぞれC3、C5を活性化する

[1] L. R. McDowell, Vitamins in animal and human nutrition, http://books.google.co.uk/books?id=dXOPBMYIPcQC&pg=PA526

[MechB12-2] David Dophin. Preparation of the Reduced Forms of Vitamin B₁₂ and of Some Analogs of the Vitamin B₁₂ Coenzyme Containing a Cobalt-Carbon Bond. D.B. McCormick and L.D. Wright, Eds. 1971;Vol. XVIII:34-54.

[3] 1. J. C. Fontecilla-Camps, P. Amara, C. Cavazza, Y. Nicolet and A. Volbeda, "Structure-function relationships of anaerobic gas-processing metalloenzymes", Nature 2009, volume 460, p. 814-822.doi:10.1038/nature08299

[4] Zenon Schneider, Andrzej Stroiński, Comprehensive B12: Chemistry, Biochemistry, Nutrition, Ecology, Medicine, http://books.google.co.uk/books?id=OBlxCKbYCx8C&pg=PA32

匿名

検索

案内

案内

methyl-B12