[UV-Vis absorption spectral characteristics of tobacco peroxidase I from Nicotiana tabacum].

The ultraviolet/visible spectra of TOP I were studied. It was proved that TOP I is an acid enzyme containing it hemochrome as an agon. When the pH reduced, the Soret absorption in UV-Vis region exhibited a blue shift, when pH increased exhibited a red shift. The result of the influence of carbamide, the denaturant, on the spectra showed that TOP I may have a unfolded structural change in the solution, which made the peptide chain completely extend. After adding Fe(III), Fe(II), Cu(II), Zn(II), Co(II), Ni(II) and Sn(II) to the apo-TOP I, the UV-Vis spectra changed except for Fe(III), which almost did not change at all. The strongest characteristic absorption peak of the Soret showed a blue shift to different extent and it became weak gradually. The situation of alpha-strip and beta-strip remained unchanged while the relative strength decreased.