title: Characterization of a novel endonuclease from Crithidia fasciculata.
abstract: A new endonuclease activity has been identified in whole cell lysates of the trypanosomatid Crithidia fasciculata. This activity, termed endonuclease A (Endo A), introduces single-strand breaks at highly preferred sites in double stranded DNA substrates Physical analysis of this enzyme indicates that it has a sedimentation coefficient S20,W of 4.9 and a Stokes radius of 59A and thus, a native molecular weight of 125,000 and a frictional coefficient of 1.8. A monomeric structure is suggested for the enzyme based on the recovery of Endo A activity associated with a polypeptide with a molecular weight of 116,000-120,000, following electrophoresis on sodium dodecyl sulfate polyacrylamide gels. Endo A shows an absolute requirement for Mg2+ or Mn2+ and exhibits activity over a broad pH and temperature range, with optimal conditions for activity at pH 8.0 and 30 degrees C.
authors.affiliation: Molecular Biology Institute, University of California, Los Angeles 90024.
authors.forename: M L
authors.initials: ML
authors.lastname: Holdsworth
authors.forename: J C
authors.initials: JC
authors.lastname: Hines
authors.forename: D S
authors.initials: DS
authors.lastname: Ray
mesh_terms: D000818:Animals; D001483:Base Sequence; D002499:Centrifugation, Density Gradient; D003421:Crithidia / Q000201:enzymology*; D015342:DNA Probes; D004720:Endonucleases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013379:Substrate Specificity
chemical_list: D015342:DNA Probes; D004720:Endonucleases