氨基酰化酶与Cu(Ⅱ)相互作用的谱学研究

Study on the Direct Interaction between Aminoacylase and Cu(Ⅱ) Ions by Spectroscopic Analysis

通过顺磁共振法、可见光谱法及酶活性测量研究从猪肾中提纯的氨基酰化酶 (Aminoacylase,简称ACY)在pH 4 0条件下与外加的Cu(Ⅱ )离子存在直接相互作用。结果发现 :外加Cu(Ⅱ )离子进入ACY活性中心位点 ,取代了活性中心位点的Zn(Ⅱ ) ,使酶活性下降。

In this paper,the method of reconstitution was used to investigate the interaction between metalloenzymes (containing Zn(Ⅱ)) and metal ions.Electron paramagnetic resonance(EPR),visible spectrum (Vis) and enzyme activity assay have been employed to study the direct interactions between aminoacylase (ACY) and Cu(Ⅱ) ions added in aqueous solution.The results show that a dynamic equilibrium exists between the Zn(Ⅱ) in the active site of native enzymes and the added Cu(Ⅱ),the added Cu(Ⅱ) partly replaces the Zn(Ⅱ),forming Cu(Ⅱ) enzyme derivatives.As a result,the activity of the native enzymes is influenced.In addition,the influences of pH value on this kind of interaction have also been investigated,and the results demonstrate that the decrease in the intensity of the Cu(Ⅱ) EPR signal and the change of place signal in Vis were observed as increase of pH value.These results suggest that the derivative of Cu(Ⅱ) ACY exists in solution with two different conformations,and this two conformations exchanged each other depending on pH.