Purification and characterization of iso-ribonucleases from a novel thermophilic fungus

Int J Mol Sci. 2014 Jan 10;15(1):944-57. doi: 10.3390/ijms15010944.


A thermophilic fungus previously isolated from composted horse manure was found to produce extracellular iso-RNases that were purified 127.6-fold using a combination of size exclusion chromatography and a novel affinity membrane purification system. The extent of purification was determined electrophoretically using 4%-15% gradient polyacrylamide gels. RNase activity was dependent on the presence of a metal co-factor with significantly more activity with Zn2+ or Mn2+ than Mg2+. The RNases exhibited maximum activity at both pH 3.0 and pH 7.0 with no activity at pH 2.0 or 10.0. The optimal temperature for the iso-RNase was 70 °C. The molecular weight of the iso-RNase was determined to be 69 kDa using a Sephadex G-75 column.

MeSH terms

  • Cations, Divalent / chemistry
  • Chaetomium / enzymology*
  • Fungal Proteins / chemistry*
  • Ribonucleases / chemistry*


  • Cations, Divalent
  • Fungal Proteins
  • Ribonucleases