A Barley Endonuclease Specific for Apurinic DNA

Abstract

An endonuclease specific for depurinated native DNA was isolated and partially purified from extracts of barley leaves. The procedure included streptomycin sulphate precipitation. ammonium sulphate fractionation, phosphocellulose, hydroxyapatite and Sephadex G-150 chromatography. Purityo of the resulting enzyme was determined by gel electrophoresis and gel chromatogrphy and specificity be testing the activity on intact and depurinated bacterial DNAs. At lower concentrations. the enxyme is specific for DNA containing apurinic sites. At higher concentrations, however, it degrades DNA in a non-specific manner. the nuclease has a pH optimum at 7.6, and a molecular weight of about 18000.