Purification, molecular and enzymic characterization of an acid RNase from the insect Ceratitis capitata

Eur J Biochem. 1986 Jul 15;158(2):367-72. doi: 10.1111/j.1432-1033.1986.tb09760.x.


An acid ribonuclease has been purified from the insect Ceratitis capitata. The specific activity of the purified enzyme is 580 units/mg. This enzyme is a single polypeptide chain of about 35.5 kDa, containing only one disulfide bridge and no free -SH groups. The A0.1%1cm at 280 nm is 1.90. The hydrodynamic radius of the native enzyme is 2.5 nm. The secondary structure of this RNase is composed of 10% alpha-helix, 31% beta-structure and 59% aperiodic conformation with an average number of residues per helical segment of 10, based on circular dichroic measurements. Optimum parameters for the enzyme activity are pH 5.5, 0.15 M ionic strength and 40 degrees C. Divalent cations are not required for the enzymic catalysis. This enzyme has been characterized as cyclizing endoribonuclease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / analysis
  • Animals
  • Hydrogen-Ion Concentration
  • Insecta / enzymology*
  • Molecular Weight
  • Protein Conformation
  • Ribonucleases / analysis*
  • Ribonucleases / isolation & purification
  • Spectrum Analysis


  • Amino Acids
  • Ribonucleases