title: A Mg2+-independent Ca2+-stimulated ATPase activity in the tegument of Schistosoma mansoni.
abstract: A tegumental fraction was prepared from Schistosoma mansoni. This fraction exhibited ATPase activity stimulated by Ca2+ in the absence of Mg2+. The Mg2+ independency was assessed by lowering contaminant Mg2+ using CDTA. The peak of activity was 220 mumol Pi mg-1 protein h-1 and the K0.5 for CaATP was 0.32 mM; the same K0.5 was obtained using MgATP as substrate, in the absence of Ca2+. Both activities may be promoted by the same enzyme since the addition of Ca2+ did not increase the ATPase activity measured in the presence of a saturating MgATP concentration.
authors.affiliation: Departamento de Farmacologia Básica e Clínica, Universidade Federal do Rio de Janeiro, Brasil.
authors.forename: V M
authors.initials: VM
authors.lastname: Cunha
authors.forename: F
authors.initials: F
authors.lastname: Noël
mesh_terms: D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000096:biosynthesis*; D000252:Calcium-Transporting ATPases / Q000096:biosynthesis*; D004789:Enzyme Activation; D008297:Male; D012550:Schistosoma mansoni / Q000201:enzymology*
chemical_list: D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases