[Study on the direct interaction between aminoacylase and Cu(II) ions by spectroscopic analysis]

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.