Open AccessSingle‐Strand‐Specific Nuclease from the Nucleoplasm of Rye Germ Nuclei
Author(s) -
PRZYKORSKA Anna,
SZARKOWSKI Jan W.
Publication year - 1980
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1980.tb04722.x
Subject(s) - nuclease , nucleoplasm , micrococcal nuclease , dna , endonuclease , biochemistry , polynucleotide , chemistry , nucleic acid , phosphomonoesterase , biology , chromatin , enzyme , nucleolus , nucleosome , phosphatase , cytoplasm
The localization of DNAase activity in rye germ nuclei revealed 48% of the total nuclear activity in the nucleoplasm and 4% in the chromatin. 2. The endonuclease present in the nucleoplasm was purified more than 300‐fold as compared with the specific activity in homogenized nuclei by means of ammonium sulphate fractionation and CM‐cellulose and CM‐Sephadex column chromatography. The preparation gave a single band on polyacrylamide gels. Its molecular weight is 45000, pH optimum 5.4. The preparation does not exhibit activity of non‐specific phosphomonoesterase and phosphodiesterase. 3. The nuclease catalyses the hydrolysis of denatured DNA and RNA to acid‐soluble 5′‐phoshate‐terminated products and cleaves the phosphomonoester linkage of 3′AMP. 4. Synthetic polyribonucleotides are hydrolysed at a rate decreasing in the order: poly(U) > Poly(A) > Poly(C) > Poly(G). 5. The endonuclease shows a high preference for single‐stranded nucleic acids. It does not depolymerise double‐stranded poly(U)· poly(A). 6. The nuclease attacks covalently closed circular bacteriophage PM2 DNA, plasmid ColE1 and plasmid pBR322 DNA, converting it initially into the open‐circular (relaxed) form and subsequently into the linear form. This reaction is strongly dependent on ionic strength. 7. The enzyme nicks the supercoiled DNA molecule of phage PM2 in only one place. At high enzyme concentrations several nicks in such a molecule are observed.