title: Mechanism of action of cobalt ions on rat osseous plate alkaline phosphatase.
abstract: Polidocanol-solubilized osseous plate alkaline phosphatase was modulated by cobalt ions in a similar way as by magnesium ions. For concentrations up to 1 microM, the Chelex-treated enzyme was stimulated by cobalt ions, showing Kd = 6.0 microM, V = 977.5 U/mg, and site-site interactions (n = 2.5). Cobalt-enzyme was highly unstable at 37 degrees C, following a biphasic inactivation process with inactivation constants of about 0.0625 and 0.0015 min-1. Cobalt ions stimulated the enzyme synergistically in the presence of magnesium ions (Kd = 5.0 microM; V = 883.0 U/mg) or in the presence of zinc ions (Kd = 75.0 microM; V = 1102 U/mg). A steady-state kinetic model for the modulation of enzyme activity by cobalt ions is proposed.
authors.affiliation: Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brasil.
authors.forename: P
authors.initials: P
authors.lastname: Ciancaglini
authors.forename: J M
authors.initials: JM
authors.lastname: Pizauro
authors.forename: F A
authors.initials: FA
authors.lastname: Leone
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D001842:Bone and Bones / Q000201:enzymology*; D002614:Chelating Agents / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology*; D003902:Detergents; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D000077423:Polidocanol; D011092:Polyethylene Glycols; D011137:Polystyrenes / Q000494:pharmacology; D011145:Polyvinyls / Q000494:pharmacology; D051381:Rats; D012995:Solubility; D015032:Zinc / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D003902:Detergents; D011137:Polystyrenes; D011145:Polyvinyls; D000077423:Polidocanol; D003035:Cobalt; D011092:Polyethylene Glycols; C006960:chelex; D000469:Alkaline Phosphatase; D008274:Magnesium; D015032:Zinc