【摘要】 本文以日本对虾为材料提取和部分纯化酚氧化酶，并对其特性进行了研究。以邻苯二酚为作用底物，该酶的最适pH为6．5，在pH5．0－8．0范围内有较高稳定性，最稳定的pH为7．0。最适温度为40℃，在40℃以下表现出较高的热稳定性，而在50℃以上迅速失活。该酶对不同的酚类物质表现出不同的底物专一性，由高至低的趋势依次为三元酚（焦性没食子酸）、二元酚（邻苯二酚及DL－多巴）和单元酚（L－酪氨酸）。米氏常数Km值测定表明，该酶对邻苯二酚比DL－多巴有更高的亲和力。浓度15mmol／L的Vc和L－半胱氨酸对酶的活性具有强烈抑制作用，抑制效率分别为89．6％和86．0％。更多还原

【Abstract】 Phenoloxidase (PO) was extracted and partially purified from Japanese prawn, Penaeus japonicus and its properties were studied. The optimun pH for PO-pyrocate chol reaction was 6. 5. The enzyme was stable between pH 5. 0 and pH 8. 0, most stable at pH 7. 0. The optimum temperature for the oxidation of pyrocatechol by PO was 40℃and the enzyme was heat stable up to 50℃, and it was rapidly inactivated at temperature above 50℃. The enzyme had different substrate specificities for different kinds of phenolic compounds, showing a maximum activity with triphenol (pyrogallol), then with diphenols(pyrocatechol and DL-DOPA) and monophenol(L-tyrosine). The Km values of phenoloxidase indicated that the enzyme had higher affinity for pyrocatechol than for DL-DOPA. The presence of 15 mmol/L ascorbic acid or L-cysteine inhibited strongly the enzyme activity with 89. 6% or 86. 0% inhibition, respectively.更多还原