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- 虎谷 哲夫
- 岡山大学工学部生物機能工学科
書誌事項
- タイトル別名
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- Structure-Based Fine Mechanism of Action of a Vitamin B_<12> Enzyme
- ビタミンB12酵素の立体構造と精密触媒機構
- ビタミン B12 コウソ ノ リッタイ コウゾウ ト セイミツ ショクバイ キコウ
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抄録
Certain enzymes utilize the high reactivity of radicals to catalyze chemically difficult reactions. Coenzyme B_<12> serves as a cofactor for enzymatic radical reactions. The three-dimensional structures of coenzyme B_<12>-dependent diol dehydratase and glycerol dehydratase were determined by X-ray crystallography. The structure-based fine mechanism of action of diol dehydratase was studied to establish the general mechanism for B_<12> enzymes as well as radical enzymes. The steric strain model was proposed for the coenzyme cobalt-carbon bond homolysis. The ribosyl rotation model well explained the distance problem and the stereospecificity in hydrogen abstraction. The substrate-induced conformational change of the enzyme revealed the substrate triggering mechanism for the catalytic radical formation. Theoretical calculations as well as mutational studies suggested that the hydroxyl group migrates by the concerted pathway through a three-membered cyclic transition state which is stabilized by active-site amino acid residues. A refined catalytic mechanism for diol dehydratase is proposed here.
収録刊行物
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- ビタミン
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ビタミン 77 (5-6), 297-312, 2003
公益社団法人 日本ビタミン学会
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詳細情報 詳細情報について
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- CRID
- 1390282680761616768
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- NII論文ID
- 110002883527
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- NII書誌ID
- AN00207833
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- ISSN
- 2424080X
- 0006386X
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- NDL書誌ID
- 6626938
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- 本文言語コード
- ja
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- データソース種別
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- JaLC
- NDL
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可