title: Asymmetric mono- and dinuclear GaIIIand ZnIIcomplexes as models for purple acid phosphatases.
abstract: Derivatives of the known dinucleating ligands HL1(2,6-bis{[bis(pyridin-2-ylmethyl)amino]methyl}-4-methylphenol) and H2L2(2-{[bis(pyridin-2-ylmethyl)amino]methyl}-6-{[(2-hydroxybenzyl)(pyridine-2-ylmethyl)amino]methyl}-4-methylphenol) with two pivaloylamido hydrogen bond donor substituents, H3L3and H3L5, have been prepared. The mono-, homo- and heterodinuclear ZnIIand GaIIIcomplexes of these ligands have been prepared and characterized. The solution equilibria are discussed on the basis of extensive NMR spectroscopic, mass spectrometric and pH-dependent UV-vis spectroscopic titrations. The phosphoester hydrolysis activity of the complexes has been studied as a function of pH and substrate concentration and analyzed using Michaelis-Menten kinetics. It emerges that the mixed metal (mixed valent) complex of the ligand with an asymmetric disposition of the hydrogen bonding substituents (H3L3) is a functional model for the mixed valent, dinuclear metallohydrolase purple acid phosphatase. This complex combines the essential structural features of the active site of PAP and is the first heterodinuclear model complex mimicking the essential function of PAPs, i.e. the hydrolysis of phosphomonoesters.
authors.affiliation: Heidelberg University, Institute of Iorganc Chemistry, and Interdisciplinary Center for Scientific Computing, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany; The University of Queensland, School of Chemistry and Molecular Biosciences, Brisbane, QLD 4072, Australia.
authors.forename: Simone
authors.initials: S
authors.lastname: Bosch
authors.affiliation: Heidelberg University, Institute of Iorganc Chemistry, and Interdisciplinary Center for Scientific Computing, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany. Electronic address: peter.comba@aci.uni-heidelberg.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Comba
authors.affiliation: The University of Queensland, School of Chemistry and Molecular Biosciences, Brisbane, QLD 4072, Australia.
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Gahan
authors.affiliation: The University of Queensland, School of Chemistry and Molecular Biosciences, Brisbane, QLD 4072, Australia.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schenk
mesh_terms: D000135:Acid Phosphatase / Q000737:chemistry*; D000840:Anisoles / Q000138:chemical synthesis / Q000737:chemistry*; D040761:Biomimetic Materials; D020134:Catalytic Domain; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D005708:Gallium / Q000737:chemistry*; D006023:Glycoproteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D010940:Plant Proteins / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D000840:Anisoles; D056831:Coordination Complexes; D006023:Glycoproteins; D010940:Plant Proteins; D011725:Pyridines; D005708:Gallium; C091137:purple acid phosphatase; D000135:Acid Phosphatase; D015032:Zinc
keywords: Asymmetry; Dinucleating ligand; Hydrogen bonding; Kinetics; Phosphatase; Reaction mechanism