长吻鮠碱性磷酸酶的动力学研究
THE KINETICS OF ALKALINE PHOSPHATASE FROM LEIOCASSIS LINGIROSTRIS G躈THER
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摘要: 采用生化手段,从长吻鮠(Leiocassis longirostris Günther)肝中提取出碱性磷酸酶(AKP).提纯倍数为62.08倍,比活为66.43单位/mg蛋白,提取酶液经PAGE和SDS-PAGE只呈现一条区带.该酶的最适pH为10.05,7.0>pH>11.0时不稳定;最适温度为40℃,;对热不很稳定;以磷酸苯二钠为底物其Km值为1.82×10-3mol/L.Mg2+为该酶的激活剂,L-Cys、KH2PO4、DFP、ME、EDTA-Na2为抑制剂.选用KH2PO4,和DFP作抑制类型的判断,结果表明,KH2PO4,属竞争性抑制剂,其抑制常数为2.41mmol/L,DFP为非竞争性抑制剂,抑制常数为1.01mmol/L.Abstract: Alkaline phosphatase(AKP)was purified from the liver of Leiocassis longirostris by a biochemical method.The purification multiple was 6 2.0 8 and the specificactivity was 66.43 unit/mg protein,In PAGE and SDS-PAGE,the liver of Leiocassis longirostris AKP formed a single band.The optimum pH for the enzyme was pH10.05;when 7.0pH11,it was uhstable. The optimum temperature was about 40℃,it was unstable against heat.The Km value was 1.82×10-3mol/L with disodium phenyl phosphate as its substrate. The activator of the enzyme was Mg2+,while inhibitors were KH2PO4,L-Cys,ME,DFP,and EDTA-Na2,KH2PO4 and DFP were selected for determining the types of inhibhion and the results showedthat KH2PO4 was a competitive inhibitor with the inhibition constant being 2.41mmol/L,and that DFP was a noncompetitive inhibitor with the inhibition constantbeing 1.01m mol/L.
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