Figure 8
DSN activity against synthetic DNA-RNA hybrids. Ten picomoles of p25 DNA (25-mer) and 10 pM of ribo30 RNA (30-mer) were dissolved in 20 μl 25 mM Tris-HCl, pH 7.5 containing 5 mM MgCl2 and incubated with 1 Kunitz unit of DSN for 1 hr at 45°C. Reactions were stopped by adding EDTA to a final concentration of 5 mM. Products were separated by urea-polyacrylamide gel electrophoresis and analyzed autoradiographically by exposure to BioMax film (Kodak). Lanes: 1, p25, untreated; 2, p25, treated with DSN: 3, ribo30, untreated; 4, ribo30, treated with DSN; 5, ribo30 + p25, treated with DSN.