[The effect of SSB-protein from Ehrlich ascites carcinoma cells on activity of various enzymes of DNA replication and repair].

The effect of a single-stranded DNA-binding protein (SSB-protein) form Ehrlich ascites tumour cells (EAT) on the activity of homologous purified DNA-polymerases alpha and beta, DNA-replicase, primase and DNA-polymerases from phage T4 and Bacillus stearothermophillus was studied. It was shown that the SSB-protein caused a 1.5-2.5-fold stimulation of the DNA-polymerase alpha activity on different templates (e.g., denaturated and activated DNA, poly(dA). The degree of stimulation depended on the template type, protein/template ratio and purity of DNA-polymerase alpha. The activity of DNA-polymerase was inhibited by the SSB-protein, when the activated DNA was used as a matrix and was unchanged on the denaturated DNA. The activity of some prokaryotic DNA-polymerases was increased under the influence of the SSB-protein. The protein enhanced the processivity of T4 DNA-polymerase and strongly inhibited the activity of replicase and primase. A conclusion about the complex effect of the SSB-protein on the activity of replicative and repair enzymes is drawn.