Tobacco peroxidase (TOPI) has been purified by ammonium sulfate fractionation and column chromatography, involving ion exchange on DE-52 cellulose, gelfiltration on Sephadex G-75 and ion exchange on DEAE-sephadex A-50. The specific activity of peroxidase purified was 4,826 U/mg. It has been demonstrated by SDS-PAGE as a single band. Its molecular weight (matrix assisted laser desorption/ionization time of flight mass spectra) and isoelectric point (pI) have been determined to be 21,888.5 and 3.5 respectively. The native enzyme is one of a haemachrome-containing acidic protein and has its soret maximum at 402 nm and alpha and beta bands at 636 nm and 498 nm, respectively. Its characteristic absorption spectra and fluorescence spectra changed in different pH and denaturant. It has its own characteristic absorption spectra and fluorescence spectra.