中文摘要：

为研究中性植酸酶的性质，将芽孢杆菌来源植酸酶基因phy（ycD）构建到大肠杆菌表达载体pET-28a（＋）上，进行诱导表达，利用Ni—NAT和Superdex-75纯化后，对重组植酸酶r-phy（ycD）的性质进行分析．结果硅示，该酶是Ca2＋依赖性酶，Ca2＋最通浓度l为1mmol／L，酶比活为4．7U／mg，酶促反应的最适pH为6．5，在中性条件下稳定，最适反应温度为45℃，Km值和Vmax值分别为0．213mmol／L和5．55U／mg．Zn2＋、Ni2＋、Ba2＋和Ag2＋对酶促反应均有显著抑制作用，本研究表明，Ca2＋对该类酶的活性和热稳定性起着关键性作用，因此在表达和纯化过程中需要在培养基和纯化所需的各类缓冲液中添加Ca2＋．图3表1参22

英文摘要：

Phytase gene phy （ycD） from Bacillus subtilis was cloned into a pET-28a（＋） expression vector and expressed in Escherichia coli. The phytase phy（ycD） was purified by Ni-NAT and Superdex-75. This phytase was a Ca2＋ dependent enzyme, with optimum enzymatic Ca2＋ concentration 1 mmol/L. Specific activity of this phytase was 4.7 U/mg. The phytase was stable in neutral environment with optimum pH 6.5 and optimum reaction temperature 45 ℃. Zn2＋, Ni2＋, Ba：＋ signifcantly inhibited the phytase activity. The Km and Vmax values were 0.213 mmol/L and 5.55 U/mg, respectively. Ca2＋ plays a very important role on its activity and thermostability, therefore Ca2＋ should be added to the solution during the expression and purification.