title: [Purification and properties of a releasing factor of polynucleotide phosphorylase from sarcoma M-1 of rat].
abstract: A releasing factor (RF) of polynucleotide phosphorylase (PNPase) isolated and purified from sarcoma M-1 of the rat is a protein with molecular weight of about 8000 and the isoelectric point at 4,0--4,2. The process of PNPase release from the polyribosomes of normal rat liver does not depend on the pH of the medium within the pH range of 7,2--9,0, on temperature within the interval of 0--400 degrees and on incubation time. Inhibition of phosphorolysis by endogenous RNA from normal rat liver polyribosomes requires considerable amounts of RF--approximately 170--800 molecules of RF per molecule of poly(A)+-mRNA. The data obtained suggest that PNPase release from the polyribosomes under the action of RF is not a catalytic process and is caused by competition between RF and PNPase for the binding sites on the mRNA molecule.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D007700:Kinetics; D008970:Molecular Weight; D011117:Polyribonucleotide Nucleotidyltransferase / Q000302:isolation & purification / Q000378:metabolism*; D012333:RNA, Messenger; D051381:Rats; D012513:Sarcoma, Experimental / Q000201:enzymology*
chemical_list: D012333:RNA, Messenger; D011117:Polyribonucleotide Nucleotidyltransferase
vernacular_title: Ochistka i kharakteristika faktora sniatiia polinukleotidfosforilazy iz sapkomy M-1 krys.