cobalamin

ビタミンB12 vitamin B12

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/06/21 00:10:39」(JST)

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Cobalamin with the upper axial ligand noted as R

Cobalamin may refer to several chemical forms of vitamin B₁₂, depending on the upper axial ligand of the cobalt ion. These are:

• Cyanocobalamin (R = –CN)
• Hydroxocobalamin (R = –OH)
• Methylcobalamin (R = –CH₃), an active form of vitamin B₁₂
• Adenosylcobalamin (R = –Ado), also an active form of vitamin B₁₂

Cobalamin is susceptible to acid. During its biosynthesis complexes are formed to protect it.

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• 1. 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
• 2. 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
• 3. ビタミンB12および葉酸欠乏症の生理学 physiology 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. 疾患予防におけるビタミン補給 vitamin supplementation in disease prevention

English Journal

• Genomic approach to studying nutritional requirements of Clostridium tyrobutyricum and other Clostridia causing late blowing defects.

• Storari M1, Kulli S1, Wüthrich D2, Bruggmann R2, Berthoud H1, Arias-Roth E3.
• Food microbiology.Food Microbiol.2016 Oct;59:213-23. doi: 10.1016/j.fm.2016.05.013. Epub 2016 May 26.
• Clostridium tyrobutyricum is the main microorganism responsible for the late blowing defect in hard and semi-hard cheeses, causing considerable economic losses to the cheese industry. Deeper knowledge of the metabolic requirements of this microorganism can lead to the development of more effective c
• PMID 27375262

• Molecular characterization of methanogenic N(5)-methyl-tetrahydromethanopterin: Coenzyme M methyltransferase.

• Upadhyay V1, Ceh K1, Tumulka F2, Abele R2, Hoffmann J3, Langer J1, Shima S4, Ermler U5.
• Biochimica et biophysica acta.Biochim Biophys Acta.2016 Sep;1858(9):2140-4. doi: 10.1016/j.bbamem.2016.06.011. Epub 2016 Jun 21.
• Methanogenic archaea share one ion gradient forming reaction in their energy metabolism catalyzed by the membrane-spanning multisubunit complex N(5)-methyl-tetrahydromethanopterin: coenzyme M methyltransferase (MtrABCDEFGH or simply Mtr). In this reaction the methyl group transfer from methyl-tetrah
• PMID 27342374

• Toward Quantitatively Accurate Calculation of the Redox-Associated Acid-Base and Ligand Binding Equilibria of Aquacobalamin.

• Johnston RC1, Zhou J, Smith JC, Parks JM1.
• The journal of physical chemistry. B.J Phys Chem B.2016 Aug 4;120(30):7307-18. doi: 10.1021/acs.jpcb.6b02701. Epub 2016 Jul 22.
• Redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. A major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociati
• PMID 27391132

Japanese Journal

• Characterization of vitamin B₁₂ compounds in the fruiting bodies of shiitake mushroom (Lentinula edodes) and bed logs after fruiting of the mushroom

• Bito Tomohiro,Teng Fei,Ohishi Noriharu [他]
• Mycoscience : official journal of the Mycological Society of Japan 55(6), 462-468, 2014-11
• NAID 40020205766

• Molecular Modeling Studies and Synthesis of Novel Methyl 2-(2-(4-Oxo-3-aryl-3,4-dihydroquinazolin-2-ylthio)acetamido)alkanoates with Potential Anti-cancer Activity as Inhibitors for Methionine Synthase

• Elfekki Ismail Mahmoud,Hassan Walid Fathalla Mohamed,Elshihawy Hosam Eldin Abd Elhamed [他]
• Chemical and pharmaceutical bulletin 62(7), 675-694, 2014-07
• NAID 40020103578

• Molecular Modeling Studies and Synthesis of Novel Methyl 2-(2-(4-Oxo-3-aryl-3,4-dihydroquinazolin-2-ylthio)acetamido)alkanoates with Potential Anti-cancer Activity as Inhibitors for Methionine Synthase

• Elfekki Ismail Mahmoud,Hassan Walid Fathalla Mohamed,Elshihawy Hosam Eldin Abd Elhamed,Ali Ibrahim Ahmed Ibrahim,Eltamany Elsayed Hussein Mostafa
• Chemical and Pharmaceutical Bulletin 62(7), 675-694, 2014
• … Cobalamin-dependant cytosolic enzyme methionine synthase (MetS) catalyses the transfer of a methyl group from the methyltetrahydrofolate (MTHF) to homocysteine (Hcy) to produce methionine and tetrahydrofolate (THF). …
• NAID 130004053811

Related Links

• Vitamin B-12 (Cobalamin) for Fatigue, Memory Loss, Weakness

Vitamin B-12 (cobalamin) plays a role in making DNA and also helps keep nerve cells and red blood cells healthy. Why do people take vitamin B-12? Vitamin B-12 has been looked at as a treatment for many diseases and conditions.

• Cobalamin: Diagnostic use and therapeutic considerations ...

Cobalamin Deficiency in Gastrointestinal Disease In animals with reduced cobalamin absorption, regardless of the cause, it is reasonable to expect that eventual depletion of bodily cobalamin stores will occur and cobalamin deficiency ...

Related Pictures

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★リンクテーブル★

リンク元	「ビタミンB12」「vitamin B12」
拡張検索	「hydroxocobalamin hydrochloride」「5'-deoxyadenosylcobalamin」「cobalt 57-cyanocobalamin」「transcobalamin」

「ビタミンB12」

　　[★]

英

vitamin B12

同

コバラミン cobalamin

商

アリチア配合

関

シアノコバラミン、悪性貧血、ビタミン、メチルコバラミン

• 構造：FB.387

吸収

• 食物(コバラミン＋蛋白質)→胃(コバラミン)＋壁細胞が分泌する糖タンパク;内因子→コバラミン-内因子複合体→回腸 (SP.742)

回腸上皮細胞の刷子縁膜にコバラミン-内因子複合体に特異的なレセプターが存在 (SP.742)

細胞内ではβグロブリン(トランスコバラミン II)と結合して血中に入り組織に運ばれる (SPC.280, SPC.742)

部位：　ビタミンB12は回腸。　葉酸は空腸。　鉄も空腸、ついでに十二指腸でも。

機能

• コバラミン依存の酵素は全部で十数種ある。コバラミン依存の酵素は分子内転移、メチル転移を触媒 (FB.387)
• 正常ミエリンの維持 (SPC.280)
• 葉酸の代謝(葉酸は核酸代謝に関わっている) (SPC.280)
• 奇数脂肪酸の酸化 (FB.386)

メチルマロニルCoAムターゼの補酵素(奇数脂肪酸の酸化)

補酵素

• methylmalonyl-CoA mutase：
• methionine synthase：homocysteine + methyl THF－→methionine + THF

必要量

• 一日の消費量(排泄)：1-3ug (体の貯蔵量の-0.1%) (HIM.643)
• 体に貯蔵されてる量：2-3mg　→　摂取しなくとも3-4年は欠乏しない

基準値

• 260-1,050pg/ml(192-775pmol/ml)

判定

低値

• 巨赤芽球貧血

• 悪性貧血(内因子抗体、壁細胞抗体？)
• 胃切除後
• 萎縮性胃炎

• 吸収不良をきたす病態：クローン病、セリアック病、吸収不良症候群

高値

• 血液疾患：顆粒球増加を示す疾患　　　←　　顆粒球由来のビタミンB12輸送蛋白(トランスコバラミン?)が増加するため(QB.G-257)、崩壊した白血球から放出するため(YN.G-53)

• 慢性骨髄性白血病、真性多血症

臨床関連

• ビタミンB₁₂欠乏症
• 悪性貧血
• 慢性骨髄性白血病

• 白血球の破壊により末梢へのビタミンB12の漏出

• 亜急性連合性脊髄変性症 SCDC

• http://www.shc.usp.ac.jp/shibata/5-16-4.pdf

「vitamin B12」

　　[★] ビタミンB12 cobalamin

「hydroxocobalamin hydrochloride」

　　[★]

• 塩酸ヒドロキソコバラミン

関

hydroxocobalamin、hydroxocobalamin acetate

「5'-deoxyadenosylcobalamin」

　　[★] 5-デオキシアデノシルコバラミン

「cobalt 57-cyanocobalamin」

　　[★] コバルト57-シアノコバラミン

「transcobalamin」

　　[★]

トランスコバラミン