Spectroscopic Analysis of the Zinc Ion Interaction with Horseradish Peroxidase.

The purpose of the current study was to evaluate the interaction between zinc ions and horseradish peroxidase (HRP) by ultraviolet-visible, fluorescence, circular dichroism, and FTIR spectroscopies. HRP conformation analysis revealed a noticeable decrease in α-helix from 47% for the free enzyme to 17% for HRP–Zn2+ and a reduction in tertiary structures of the enzyme through a Zn2+ interaction. Moreover, the fluorescence intensity of HRP was decreased significantly by Zn2+. The linear relationship of HRP emission data and inhibitor concentration indicated that the extinction process is linear and occurs uniformly with increasing Zn2+ concentration. The values of Kq for the zinc and HRP interaction were in the order of 1011 L/mol, which means that HRP fluorescence was quenched by Zn2+ through a static quenching mechanism. [ABSTRACT FROM AUTHOR]