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題名 | 基隆山藥塊莖多酚氧化酶之純化及性質研究=Studies on the Purification and Properties of Polyphenol Oxidase from Keelong Yam Tubers |
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作者姓名(中文) | 王俐婷; 朱賢一; 張珍田; | 書刊名 | 中國農業化學會誌 |
卷期 | 37:1 1999.03[民88.03] |
頁次 | 頁141-151 |
分類號 | 434.3 |
關鍵詞 | 山藥塊莖; 多酚氧化酶; 純化; 性質; Yam tubers; Polyphenol oxidase; Purification; Properties; |
語文 | 中文(Chinese) |
中文摘要 | 基隆山藥塊莖經丙酮乾燥處理,所含多酚氧化�t以緩衝液抽取、硫酸銨劃分、 Sephacryl S-100HR膠體過濾層析、DEAE-Sephacel離子交換層析及Sephacryl S- 300HR 高效膠體過濾層析等連續系列步驟純化。純化之酵素以膠體過濾法測得原態分 子量為283kDa,以SDS-PAGE測得次單元分子量為72 kDa,因此為一含4個次單 元之寡聚酵素。以native-PAGE配合多酚氧化�t活性染色,發現純化之酵素含有6種 同功異構�t。由基質專一性測定顯示純化之多酚氧化�t僅具佯化鄰位二元酚活性,不 具氧化單元酚活性。其氧化兒茶酚(pyrocatechol)之最適pH為6,最適溫度為20 ℃,銅離子螯合劑sodium diethyl dithiocarbamate (0.36mM),金屬離子錯合物形 成劑硫尿(thiourea, 0.1mM)、氰化鉀(0.2mM),硫醇化合物β-mrpto鴟thnol (0.05mM),以及還原劑Na�特�烙�N(0.09mM)、NaHSO��(0.18mM)和ascorbic acid(0.02mM)等均在極低濃度下完全抑制酵素活性。其中還原劑之抑制作用可能為 將產物還原或與可利用之氧結合,而非使酵素分子失活。 |
英文摘要 | Polyphenol oxidase was purified from Keelong yam tubers through successive steps of acetone powder preparation, buffer extraction, sephacryl S-100 HR gel filtration, DEAE-Sephacel ion-exchange chromatography and "Sephacryl S-300 HR gel filtration. The molecular mass of the purified enzyme was 283 kDa, as determined by gel filtration. The molecular mass o f the subunit of the enzyme was 72 kDa, ad determined by SDS-PAGE. Thus, the enzyme is an oligomeric enzyme containing 4 subunits. Six isozymes of polyphenol oxidase were detected, as examined by native-PAGE and stained for polyphenol oxidase activity. From the substrate specificity determination, the purified polyphenol oxidase showed only o-diphenolase activity and no activity toward monophenols. The enzyme had an optimal pH of 6 and an optimal temperature of 20 ℃ for oxidation of phrocatechol. Cupric ion chelating vcompound, sodium diethyl dithiocarbamate (0.36mM), the metal complexing agents thiourea (0.1mM) and KCN(0.2mM), thiol compound, β -mercaptoethanol(0.05mM), and the reducing agents Na �� S �� O �N (0.09mM), NaHSO �� (0.18mM) and ascorbic acid (0.02mM) completely inhibited the activity of the enzyme at very low concentrations. The inhibition of the enzyme activity by the reducing agents is probably due to reduction of the product or consumption of oxygen in the reaction mixture by the reducing agents and not due ot inactivation of the enzyme molecule. |
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