[Kinetic properties of peroxidase from intact and virus-infected tobacco leaves].

The kinetic properties of peroxidase from tobacco leaves (var. Xanthie and Samsun) infected with various viruses (TMV, Xt and Xy, were compared. The enzyme from intact plant grown under similar conditions was used as control. The pH dependencies of the peroxidase activity for o-dianisidine peroxidation in infected and control plants were identical. Viral infection produces a dramatic effect on the kinetic properties of the enzyme: the KM values for o-dianisidine were decreased by 20-40% and those for H2O2 - by 30-40% in the case of the Samsun var. infected with TMV and Xanthie var. infected with a highly virulent strain of potato X-virus. The decrease of these values in plants infected with a weakly virulent strain of the virus was insignificant.