Nucleases in chloroplast of barley |
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Authors: | Jiřina Švachulová J Velemínský J Šatava |
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Institution: | (1) Institute of Experimental Botany, Czechoslovak Academy of Sciences, Flemingovo n. 2, 160 00 Praha 6, Czechoslovakia |
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Abstract: | Two barley chloroplast nuclease fractions were separated by the affinity chromatography and gel electrophoresis. Both were
about 2 times more active to RNA than to native DNA and about half as active to denaturated DNA as to native DNA. Both fractions
were as active to UV-irradiated (270 J m-2) native DNA as to intact DNA but their action was inhibited by apurinic sites. The enzyme activities were inhibited by high
concentrations of EDTA, NaCl, Mn2+, Ca2+, Zn2+ ions and by N-ethylmaleimide. They do not require Mg2+ ions but are stimulated or at higher concentration inhibited by their presence. Both RNase and DNase were active over a wide
pH range (5.5–9), the optimum for DNase action in the presence of Mg2+ being 6.5, for RNA decomposing activity at pH 8.0. As no mononucleotides were detected in acid soluble form, it seems likely
that DNase acts in the endonucleolytic way. |
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