title: Purification, molecular and enzymic characterization of an acid RNase from the insect Ceratitis capitata.
abstract: 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.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D006863:Hydrogen-Ion Concentration; D007313:Insecta / Q000201:enzymology*; D008970:Molecular Weight; D011487:Protein Conformation; D012260:Ribonucleases / Q000032:analysis* / Q000302:isolation & purification; D013057:Spectrum Analysis
chemical_list: D000596:Amino Acids; D012260:Ribonucleases