A New DNA-exonuclease in Cells Infected with Herpes Virus: Partial Purification and Properties of the Enzyme

Abstract

Infection of BHK 21 (C 13) or HEp-2 cells with herpes virus was followed by a marked increase in the activity of alkaline DNase which was prevented by actinomycin D and puromycin. Activation of a latent enzyme was not responsible for the increase. The properties of the DNase appearing after virus infection in both cell types were the same, but they differed from those of the enzyme from uninfected cells in specificity towards the secondary structure of the DNA substrate, heat-stability, requirement for thiol groups, inhibition by K⁺ and Na⁺ ions and response to various concentrations of Mg²⁺ and Mn²⁺. The activities of acid DNase and alkaline phosphomonoesterase were not significantly altered after herpes infection. Further, the activity of alkaline RNase was not altered by infection, and this implies that the induced DNase was specific for DNA. The new DNase could be separated from the DNase present in uninfected cells and from alkaline phosphomonoesterase by chromatography on columns of DEAE-cellulose; its enzymic properties were the same as those observed with soluble extracts of cells infected with herpes virus.