金属离子对长毛对虾酸性磷酸酶的影响

Effect of metal ions on Penaeus pencinillatus acid phosphatase

本文研究几种金属离子分别对健康虾和病虾酸性磷酸酶ACPase（EC3．1．3．2）活力的影响。结果表明，Ni2＋、Mg2＋、Cd2＋对酶无明显抑制作用，Zn2＋、Cu2＋、Hg2＋对酶活力抑制明显。当Hg2＋离子浓度达0．5mmol／dm3时，酶活力被抑制96％（健康虾）和95％（病虾）；各金属离子对酶的抑制强度依次为Hg2＋＞Cu2＋＞Zn2＋＞Pb2＋＞Cd2＋、Mg2＋＞Ni2＋；健康虾酶对Hg2＋、Cuv、Zn2＋、Pb2＋敏感性大于病虾酶。随着Cu2＋、Hg2＋浓度加大，抑制作用增强，表现为竞争性抑制类型，抑制常数Ki值分别为1．6×10－4mol／dm3和和1．0×10－4mol／dm3。不同浓度Hg2＋离子分别与酶作用后，测定酶的紫外吸收光谱和荧光发射光谱，从光谱的变化表明，Hg2＋离子影响酶活力同时也影响酶的构象。

The effect of several metal ions on the activity of ACPase of Penaeus pencinillatus Al-cock is studied- The experimental results show that Hg2+>Cu2+>Zn2+ >Pbz+ inhibit the en-zyme activity distinctly whereas Ni2+,Mg2+,Cd2+ slightly affect the activity of ACPase. Cu2+and Hg2+ ions are strongly competitive inhibitors,the Ki are found to be 1. 6×10-4 mol/dm3and 1. 0×10-4 mol/dm3 respectively. The changes of the UV-spectra and the fluorescence emitting spectra of ACPase affected by metal ions suggest the changes in enzyme conforma-tion and catalytic activity.