【摘要】 本文研究了底物(植酸)、产物类似物(钒酸盐)和产物(磷酸盐)对植酸酶的活力影响。研究发现当植酸的浓度小于0.6mmol/L时,反应速度随着底物浓度的增加而增大;当植酸的浓度在0.6～1.6mmol/L范围内时,反应速度变化不大,维持一个平台期;而当浓度大于1.6mmol/L时,反应速度随着底物浓度的增加而降低,高浓度植酸对植酸酶有明显的抑制作用,动力学分析表明底物抑制常数K′s为2.0mmol/L。分别以植酸和对硝基苯磷酸二钠(pNPP)做底物时研究了钒酸盐对植酸酶的抑制作用,均表现为非竞争性抑制,抑制常数Ki分别为68.29μmol/L和2.42μmol/L。磷酸盐对植酸酶表现为竞争性抑制类型,抑制常数Ki值为1.45mmol/L。更多还原

【Abstract】 This paper studied the effects of a substrate, a product (phosphate) and its analog (vanadate) on the phytase activity. When the concentration of phytate was less than 0.6 mmol/L, the reaction rate increased with the increasing concentration of phytate. And when it was between 0.6 mmol/L and 1.6 mmol/L, the reaction rate changed little, but when it was more than 1.6 mmol/L, the reaction rate decreased with the increasing concentration of phytate. The result showed that high concentrations of phytate inhibited the phytase activity. The K’s value for phytate was estimated to be 2.0 mmol/L. The enzyme activity was inhibited by vanadate with phytate and pNPP as substrate, respectively. The inhibition type was uncompetitive, with the Ki values 62.89 μmol/L and 2.42 μmol/L, respectively. The enzyme activity was also inhibited by phosphate with pNPP as substrate and the inhibition type was competitive with the Ki 1.45 mmol/L.更多还原