title: [Polynucleotide phosphorylase from rat liver nuclei. Determination of the activity and some properties].
abstract: The activity of polynucleotide phosphorylase (PNPase) from rat liver nuclei isolated in aqueous and non-aqueous media was studied. It was shown that aqueous and non-aqueous nuclear preparations differ both in specific activity (106 and 39 units per mg of protein, respectively) and in the enzyme content (11.2 and 3.4% of homogenate activity, respectively). Nuclear PNPase reveals its maximal activity at pH 7.6-8.0 and requires Mg2+. The enzyme catalyzed polyribonucleotide phosphorelysis in the following order: poly (A) leads to poly(U) leads to poly(S) leads to RNA leads to poly(A) . poly(U). It is concluded that a comparatively low PNPase activity of the nuclei isolated in sucrose media is due to the enzyme extraction from the nuclei in the course of isolation.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D011117:Polyribonucleotide Nucleotidyltransferase / Q000378:metabolism*; D011131:Polyribonucleotides; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D011131:Polyribonucleotides; D011117:Polyribonucleotide Nucleotidyltransferase; D008274:Magnesium
vernacular_title: Polinudleotidfosforilaza iader pecheni krys. Obnaruzhenie aktivnosti i nekotorye svoĭstva.