Degradation of nucleic acids in cell lysates by S1 nuclease in the presence of 9 M urea and sodium dodecylsulfate.

Single-strand-specific nuclease S1 from Aspergillus oryzae is shown to degrade DNA and RNA in lysates of HeLa cells in the presence of 9 M urea and sodium dodecylsulfate. Free dodecylsulfate inhibits S1 nuclease. However, if the detergent is complexed with proteins prior to the addition of the enzyme, S1 nuclease can degrade nucleic acids at dodecylsulfate concentrations which would inhibit the enzyme completely if no other proteins were present. In lysates prepared from HeLa cells by treatment with dodecylsulfate and urea, the detergent is complexed by cellular proteins and therefore S1 nuclease can be used to digest DNA and RNA. DNA can be completely degraded but, even after heat-denaturation, only 60% of the cellular RNA is converted into acid-soluble material. Analysis of the acid-insoluble RNA fragments by gel filtration reveals that the majority of the degradation products is approximately of tRNA size.