长毛对虾碱性磷酸酶性质

Characterization of Alkaline Phosphatase from Penaeus Penicillatus

从长毛对虾内脏物分离提纯碱性磷酸酶，经快速蛋白液相色谱（ＦＰＩＣ）检验为单一蛋白纯．研究该酶的性质，酶的紫外吸收特征峰在２７８ｎｍ处，荧光激发峰在２８２ｎｍ处，发射光谱特征峰在３４０ｎｍ处．酶的分子量为８２０００道尔顿．酶水解ＰＮＰＰ的最适温度为４７℃、最适ｐＨ为８．２．在３７℃、ｐＨ８．３下，酶的Ｋｍ值为８．０×１０－４ｍｏｌ／Ｌ．Ｍｇ２＋对该酶有激活作用，Ｃｕ２＋、Ｈｇ２＋甲醇、乙醇，乙二醇则表现抑制作用．Ｈｇ２＋的抑制作用表现为反竞争性类型，其抑制常数为９．０×１０－５ｍｏｌ／Ｌ．

An alkaline phosephatase from penaeus penicillatus has been prepared and purified. The preparation was shown to be homogenous on FPLC. The characteristic peak of UVabsorption spectrum of the enzyme is at 278 nm; and that of the fluorescence excitation spectrum at 282 nm and the fluorescence emission spectrum at 340 nm. The molecular weight of the enzyme is 82 000 dalton. The optimun temperature of the enzyme for the hydrolysis of p-nitrophenyl phosphate is at 47℃;and the optimum pH is 8. 2. At pHS. 3; 37℃; the michaelis constant(Km) is 8. 0×10-4 mol/L . Magnesium ion enhances the enzyme activity significanty; Copper ion;Mercury ion; methanol;ethanol and ethylene glycol inhibit the enzyme activity to various extents. The inhibition of Hg2+ ion on the enzyme is found to be of uncompetitiye type and the inhibition constant is found to be 9. 0× 10-5 mol/L.