Specificity of fragmentation of DNA from pBR322 plasmid by Ca,Mg-dependent endonuclease from cell nuclei of human lymphocytes |
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Authors: | N N Khodarev A Iu Morozov I A Sokolova S S Aleksandrova I I Votrin |
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Abstract: | Fragmentation of the plasmid pBR322 DNA by a purified preparation of Ca/Mg-dependent endonuclease has been studied. It was shown that on the first steps of reaction the double-stranded cuts are introduced into the superhelical DNA independent of singlestranded ones. The doublestranded cuts are introduced into superhelical and linear DNA in 12 sites enriched with GC-pairs, 9 of them include pentanucleotide CGCGG(CCGCC) that is functionally significant. Relaxation of the plasmid DNA by topoisomerase I blocks the sitespecific action of the enzyme. Ca/Mg-dependent endonuclease is concluded to be topologically dependent enzyme, possibly, participating in the recombination processes. |
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