頁籤選單縮合
題名 | Metal-binding Site of Pigeon Liver Malic Enzyme=鴿肝蘋果酸酶金屬結合中心 |
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作者 | 周慰遠; 郭呈欽; 洪慧芝; 黃德美; 張固剛; Chou, Wei-yuan; Kuo, Cheng-chin; Hung, Hui-chih; Huang, Ter-mei; Chang, Gu-gang; |
期刊 | 醫學研究 |
出版日期 | 20010800 |
卷期 | 21:4 2001.08[民90.08] |
頁次 | 頁201-206 |
分類號 | 361.1925 |
語文 | eng |
關鍵詞 | 鴿肝蘋果酸酶; 金屬結合中心; Enzyme mechanism; Malic enzyme; Metal site; Oxidative modification; |
英文摘要 | Malic enzyme from pigeon liver is very sensitive to the metal-catalyzed oxidation, which results in rapid inactivation of the enzyme activity. The Fe²⁺-mediate Fenten chemistry oxidizes and inactivates the enzyme, which is then specifically cleaved at the peptide bond between Asp-258 and Ile-259. Site-directed mutagenesis at the conserved Asp-258 confirmed that this aspartate residue is the metal binding ligand. This conclusion is corroborated by the crystal structure of human mitochondrial malic enzyme. Other metal ligands of the enzyme include Glu-234, Asp-235, C-1 carboxylate and C-2 hydroxyl of L-malate, plus a water molecule at the active site. Binding of metal ion induces a slow conformational change of the enzyme, which may represent a structural intermediate between the open-and closed-form. The functional role of the essential metal ion in the malic enzyme-catalyzed reaction is to position correctly the substrate L-malate in the active center and to stabilize the anionic enol-pyruvate reaction intermediate. |
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