title: S1 nuclease does not cleave DNA at single-base mis-matches.
abstract: Three assays have been designed to detect the cleavage of duplex phi X174 DNA at single-base mis-matches. Studies with S1 nuclease failed to detect cleavage at mis-matches. S1 nuclease digestion at 37 and 55 degrees C failed to produce a preferential degradation of a multiply mis-matched heteroduplex when compared to a mis-match-free homo-duplex as analyzed by sedimentation on sucrose gradients. Other heteroduplex templates were not cleaved by S1 nuclease at a defined single-base mis-match when assayed by gel electrophoresis or by marker rescue. In all cases, the amount of S1 nuclease employed was at least 10-times more than that required to render a single-stranded phi X174 DNA molecule completely acid soluble. The rate of hydrolysis of single-base mis-matches by S1 nuclease was estimated to be less than 0.016% of the rate at a base in single-strand phi X174 DNA. In no instance did we detect activity by S1 nuclease directed at mis-matched sites in our template molecules. Similarly, the single-strand specific endonuclease from Neurospora crassa does not cleave heteroduplex templates at a defined single-base mis-match when assayed by marker rescue.
mesh_terms: D010584:Bacteriophage phi X 174 / Q000032:analysis; D001483:Base Sequence; D002499:Centrifugation, Density Gradient; D004279:DNA, Viral / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D006868:Hydrolysis; D015719:Single-Strand Specific DNA and RNA Endonucleases; D013379:Substrate Specificity
chemical_list: D004279:DNA, Viral; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases