title: Monoesterase activity of a purple acid phosphatase mimic with a cyclam platform.
abstract: The synthesis and characterization of a novel dinucleating ligand L (L=4,11-dimethyl-1,8-bis{2-[N-(di-2-pyridylmethyl)amino]ethyl}cyclam) and its μ-oxo-bridged diferric complex [(H(2)L){Fe(III)(2)(O)}(Cl)(4)](2+) are reported. This diiron(III) complex is the first example of a truly functional purple acid phosphatase (PAP) mimic as it accelerates the hydrolysis of the activated phosphomonoester 2,4-dinitrophenyl phosphate (DNPP). The spectroscopic and kinetic data indicate that only substrates that are monodentately bound to one of the two ferric ions can be attacked by a suitable nucleophile. This is, most probably, a terminal iron(III)-bound hydroxide. DFT calculations support this assumption and also highlight the importance of secondary interactions, exerted by the protonated cyclam platform, for the positioning and activation of the iron(III)-bound substrate. Similar effects are postulated in the native enzyme but addressed in PAP mimics for the first time.
authors.affiliation: Anorganisch-Chemisches Institut, Universität Heidelberg, INF 270, 69120 Heidelberg, Germany. peter.comba@aci.uni-heidelberg.de
authors.forename: Peter
authors.initials: P
authors.lastname: Comba
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Gahan
authors.forename: Graeme R
authors.initials: GR
authors.lastname: Hanson
authors.forename: Valeriu
authors.initials: V
authors.lastname: Mereacre
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Noble
authors.forename: Annie K
authors.initials: AK
authors.lastname: Powell
authors.forename: Ion
authors.initials: I
authors.lastname: Prisecaru
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schenk
authors.forename: Marta
authors.initials: M
authors.lastname: Zajaczkowski-Fischer
mesh_terms: D000135:Acid Phosphatase / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D005290:Ferric Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D018054:Hydrobromic Acid; D008024:Ligands; D008956:Models, Chemical; D015394:Molecular Structure
chemical_list: D005290:Ferric Compounds; D006023:Glycoproteins; D006571:Heterocyclic Compounds; D008024:Ligands; C024560:cyclam; D018054:Hydrobromic Acid; C091137:purple acid phosphatase; D000135:Acid Phosphatase