Evaluation of the aromatic amino acids microenvironments of zinc-denatured horseradish peroxidase; second- derivatives spectra analysis

In the present study, the position of aromatic amino acids as important elements in the formation and stability of the tertiary structure of zinc-denatured peroxidase has been investigated with the help of second-derivative graph analysis of spectroscopic data. For this purpose, the second- derivative of absorption and emission graphs with 10 replications in the visible UV range of circular dichroism and fluorescence spectroscopy for the enzyme in the presence of 500-100 μM zinc chloride was prepared and studied with the help of MATLAB software. The results show that zinc ions reduce the compaction of microstructures around aromatic amino acids, especially for tryptophan. However, even at a concentration of 500 μM zinc, tryptophan is not directly exposed to the hydrophilic solvent. In general, tryptophan seems to be more important than other aromatic amino acids in inhibiting the enzyme by zinc metal.