Characterization of a ribonuclease from Anacystis nidulans infected with cyanophage as-1

J. Lehmann, W. Völkl, J. Udvardy, G. Borbély, B. Sivók, G. L. Farkas

Research output: Contribution to journalArticle

2 Citations (Scopus)


In Anacystis nidulans the ribonuclease (RNase) activity is very low but is greatly increased upon phage-infection. A RNase was isolated and purified over 300-fold from A. nidulans cells infected by cyanophage AS-1. The enzyme did not attack single- or double-stranded DNA, was inactive on p-nitrophenyl phosphate or bis-p-nitrophenyl phosphate as substrates, and had neither 3′- nor 5′-nucleotidase activity. The approximate MW of the enzyme was 12000. Maximal enzyme activity was at pH 7.5. No absolute requirement for metal ions was observed, but Fe3+ stimulated and Co2+ and Ni2+ inhibited enzyme activity. The enzyme is an endonuclease which, upon exhaustive hydrolysis, produces mainly oligonucleotides (average chain-length: 3) with 3′-P termini. Analysis of the base composition of these oligonucleotides and determination of their 3′-terminal nucleosides, together with the investigation of the rate of hydrolysis of synthetic polyribonucleotides, have shown that the enzyme has a relative specificity for uridylic acid.

Original languageEnglish
Pages (from-to)541-544
Number of pages4
Issue number4
Publication statusPublished - 1979


  • Anacystis nidulans
  • Cyanophyceae
  • blue-green alga
  • cyanophage infection
  • phylogenetics.
  • ribonuclease

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Plant Science
  • Horticulture

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