[Nuclear ribonucleases and post-transcriptional changes of RNA. Specificity and other properties of rat liver nuclear endonuclease].
Some physico-chemical properties, specificity and the character of action of rat liver nuclear ribonuclease are studied. The enzyme maximal activity was observed at pH 7.5--8.0, ionic strength 0.02--0.3, Mg2+ being necessary. Nuclease is an oligomer, having molecular weight is 160000--180000 daltons and containing separate associates. Purified enzyme is free of contaminating activities (polynucleotidephosphorylase, DNAse; 5'-nucleotidase, and alkaline phosphatases). It is shown to hydrolyse polyA and RNA for endonuclease type, degradation products being oligonucleotides terminating with 5'-phosphate and 3'-hydroxyl groups. RNAse hydrolyses all phosphodiester bonds in polynucleotides, developing no specificity to the nature of bases. Relative hydrolysis rate for different substrates decreased as follows: polyA greater than yeast RNA greater than polyC greater than polyU greater than 28S rRNA greater than greater than 18S rRNA greater than polyA-polyU. The enzyme may be classified as ribonucleate-5'-nucleotidehydrolase (EC 3.1.4.9.).
D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology; D004720:Endonucleases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D046911:Macromolecular Substances; D008970:Molecular Weight; D012313:RNA / Q000378:metabolism; D051381:Rats; D012260:Ribonucleases / Q000378:metabolism*
D046911:Macromolecular Substances; D012313:RNA; D004720:Endonucleases; D012260:Ribonucleases
Iadernye ribonukleazy i posttranskriptsionnye prevrashcheniia RNK. Spetsifichnost' i drugie svoistva endoribonukleazy iader pecheni krys