A new heterobinuclear FeIIICuII complex with a single terminal FeIII–O(phenolate) bond. Relevance to purple acid phosphatases and nucleases

• DOI: 10.1007/s00775-005-0635-7
• Publication Date: 2005-04-20T12:41:25Z
• Authors: Mauricio Lanznaster; Ademir Neves; Adailton J. Borto...; Veronika V. E. Aires; Bruno Szpoganicz; Hernán Terenzi; Patricia Cardoso ...; Julie M. Fuller; Simon C. Drew; Lawrence R. Gahan; Graeme R. Hanson; Mark J. Riley; Gerhard Schenk
• Keywords: 780103 Chemical sciences; Models, Molecular; Biochemistry & Molecular Biology; 250201 Transition Metal Chemistry; XAS; Iron; Acid Phosphatase; Epr-spectra; 01 natural sciences; Catalysis; Active-site; Inorganic & Nuclear; Phosphate Diester Hydrolysis; Angstrom Resolution; Heterobinuclear (fecuii)-cu-iii Complex; Metal-ions; Organometallic Compounds; Pig Allantoic Fluid; Glycoproteins; DNA cleavage; Deoxyribonucleases; Sweet-potato; Diester Hydrolysis; Redox Properties; 540; 250204 Bioinorganic Chemistry; 0104 chemical sciences; Chemistry; Crystal-structure; EPR; Purple Acid Phosphatase; Copper

A novel heterobinuclear mixed valence complex [Fe(III)Cu(II)(BPBPMP)(OAc)(2)]ClO(4), 1, with the unsymmetrical N(5)O(2) donor ligand 2-bis[{(2-pyridylmethyl)aminomethyl}-6-{(2-hydroxybenzyl)(2-pyridylmethyl)}aminomethyl]-4-methylphenol (H(2)BPBPMP) has been synthesized and characterized. A combination of data from mass spectrometry, potentiometric titrations, X-ray absorption and electron paramagnetic resonance spectroscopy, as well as kinetics measurements indicates that in ethanol/water solutions an [Fe(III)-(mu)OH-Cu(II)OH(2)](+) species is generated which is the likely catalyst for 2,4-bis(dinitrophenyl)phosphate and DNA hydrolysis. Insofar as the data are consistent with the presence of an Fe(III)-bound hydroxide acting as a nucleophile during catalysis, 1 presents a suitable mimic for the hydrolytic enzyme purple acid phosphatase. Notably, 1 is significantly more reactive than its isostructural homologues with different metal composition (Fe(III)M(II), where M(II) is Zn(II), Mn(II), Ni(II), or Fe(II)). Of particular interest is the observation that cleavage of double-stranded plasmid DNA occurs even at very low concentrations of 1 (2.5 microM), under physiological conditions (optimum pH of 7.0), with a rate enhancement of 2.7 x 10(7) over the uncatalyzed reaction. Thus, 1 is one of the most effective model complexes to date, mimicking the function of nucleases.