[Properties of DNA-dependent RNA-polymerase from spleens of mice infected with Rauscher leukemic virus].

The properties of RNA polymerases A, B and C isolated from the spleens of mice infected with Rauscher leukemic virus were studied. The solubilized RNA-polymerases A and B were purified 150--300-fold. The dynamic changes in the activities of all forms of RNA-polymerases at different stages of leukosis were studied. At the earliest steps of leukosis a 2-fold increase in the RNA-polymerase B activity followed by a 5-fold increase in the RNA-polymerase A activity was observed. At late stages of leukosis the activity of RNA-polymerase C also showed an increase. The properties of RNA-polymerases A and B from the spleens of virus-infected mice were compared to those of the controls. In leukemic tissues the specific activities of RNA-polymerases A and B were higher as compared to those of the enzymes isolated from the spleens of non-infected mice. However, no significant differences in the enzyme properties in normal and virus-infected animals were revealed. Dihydrorifampicine (200 mkg/ml) caused a 50% inhibition of RNA polymerase A in vitro but had no effect on the activities of RNA-polymerases B and C.