title: Rat osseous plate alkaline phosphatase: mechanism of action of manganese ions.
abstract: Polidocanol-solubilized osseous plate alkaline phosphatase was modulated by manganese ions in a similar way as by zinc ions. For concentrations up to 1.0 nM, the enzyme was stimulated by manganese ions, showing site-site interactions (n = 2.2). However, larger concentrations (> 0.1 microns) were inhibitory. Manganese ions could play the role of zinc ions stimulating the enzyme synergistically in the presence of magnesium ions (Kd = 7.2 microns; V = 1005.5 U mg-1). Manganese ions could also play the role of magnesium ions, stimulating the enzyme synergistically in the presence of zinc ions (Kd = 2.2 microns; V = 1036.7 U mg-1). However, manganese ions could not substitute for zinc and magnesium at the same time since ion assymetry is necessary for full activity of the enzyme. A steady-state kinetic model for the modulation of enzyme activity by manganese ions is proposed.
authors.affiliation: Departamento de Química, Faculdade de Filosofia, Ciências e Letras/USP, Ribeirão Preto, Brasil.
authors.forename: F A
authors.initials: FA
authors.lastname: Leone
authors.forename: P
authors.initials: P
authors.lastname: Ciancaglini
authors.forename: J M
authors.initials: JM
authors.lastname: Pizauro
authors.forename: A A
authors.initials: AA
authors.lastname: Rezende
mesh_terms: D000469:Alkaline Phosphatase / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D001842:Bone and Bones / Q000201:enzymology*; D002614:Chelating Agents; D003902:Detergents; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology*; D008962:Models, Theoretical; D000077423:Polidocanol; D011092:Polyethylene Glycols; D011137:Polystyrenes; D011145:Polyvinyls; D051381:Rats; D015032:Zinc / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D003902:Detergents; D011137:Polystyrenes; D011145:Polyvinyls; D000077423:Polidocanol; D011092:Polyethylene Glycols; D008345:Manganese; C006960:chelex; D000469:Alkaline Phosphatase; D008274:Magnesium; D015032:Zinc