title: Purification and properties of 3'-nucleotidase of Leishmania donovani.
abstract: A surface membrane 3'-nucleotidase from Leishmania donovani promastigotes has been purified to SDS/PAGE homogeneity. The enzyme has apparent subunit molecular mass of 38 kDa, pI 5.8 and a broad pH optimum, 5.5-7.5. EDTA partially inhibited the enzyme activity, which was fully restored by Co2+; Mg2+, Ca2+ or Mn2+ had no effect on the activity. ZnCl2 or dithiothreitol at 1 mM was inhibitory at pH 7.5, but was without effect at pH 5.5, whereas at both pH values 5 mM of either compound inhibited the enzyme. The substrate-specificity of the purified enzyme is restricted to ribonucleoside 3'-phosphates. 3'-AMP and 3'-IMP are the best substrates, whereas ADP, ATP, 2'-deoxyadenosine 3'-phosphate and 5'-AMP are competitive inhibitors of the enzyme. The enzyme showed low latency in intact-cell preparations. The kinetic properties and the surface membrane localization of the enzyme suggest its implication in the formation of nucleosides from 3'-nucleotides of the parasite's host.
authors.affiliation: Department of Biochemistry, College of Medicine, University of Lagos, Nigeria.
authors.forename: G O
authors.initials: GO
authors.lastname: Gbenle
authors.forename: D M
authors.initials: DM
authors.lastname: Dwyer
mesh_terms: D000227:Adenine Nucleotides / Q000494:pharmacology; D000818:Animals; D002413:Cations, Divalent; D002853:Chromatography, Liquid; D004229:Dithiothreitol / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D007893:Leishmania donovani / Q000201:enzymology*; D009708:Nucleotidases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity; D015032:Zinc / Q000494:pharmacology
chemical_list: D000227:Adenine Nucleotides; D002413:Cations, Divalent; D009708:Nucleotidases; C040470:3'-nucleotidase; D015032:Zinc; D004229:Dithiothreitol