CHANGES IN SUBSTRATE-SPECIFICITY OF NATIVE AND RECOMBINANT HORSERADISH-PEROXIDASE UNDER IONIZING-RADIATION

The homogeneous recombinant horseradish peroxidase preparation from E. coli inclusion bodies exhibits higher specific activity towards ammonium 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) than the native one. The differences in substrate specificity can be assigned to the native enzyme inactivation in the course of metabolic reactions in living plant cells, while the recombinant enzyme reconstructed in vitro completely realizes the original catalytic abilities. Application of the method of radiation-induced inactivation demonstrates the existence of different binding sites for the iodide anion. ABTS. phenol, and guaiacol and allows one to assume a common character of the binding sites of phenol and o-phenylenediamine.