title: Synthesis, structure, and phosphatase-like activity of a new trinuclear Gd complex with the unsymmetrical ligand H3L as a model for nucleases.
abstract: The new trinuclear gadolinium complex [Gd(3)L(2)(NO(3))(2)(H(2)O)(4)]NO(3).8H(2)O (1) with the unsymmetrical ligand 2-[N-bis-(2-pyridylmethyl)aminomethyl]-4-methyl-6-[N-bis(2-hydroxy-2-oxoethyl)aminomethyl] phenol (H(3)L) was synthesized and characterized. The new ligand H(3)L was obtained in good yield. Complex 1 crystallizes in an orthorhombic cell, space group Pcab. Kinetic studies show that complex 1 is highly active in the hydrolysis of the substrate 2,4-bis(dinitrophenyl)phosphate (K(m) = 4.09 mM, V(max) = 2.68 x 10(-2) mM s(-1), and k(cat) = V(max)/[1] = 0.67 s(-1)). Through a potentiometric study and determination of the kinetic behavior of 1 in acetonitrile/water solution, the species present in solution could be identified, and a trinuclear monohydroxo species appears to be the most prominent catalyst under mild conditions. Complex 1 displays high efficiency in DNA hydrolytic cleavage, and complete kinetic studies were carried out (K(m) = 4.57 x 10(-4) M, k'(cat) = 3.42 h(-1), and k'(cat)/K(m) = 7.48 x 10(3) M(-1) h(-1)). Studies with a radical scavenger (dimethyl sulfoxide, DMSO) showed that it did not inhibit the activity, indicating the hydrolytic action of 1 in the cleavage of DNA, and studies on the incubation of distamycin with plasmid DNA suggest that 1 is regio-specific, interacting with the minor groove of DNA.
authors.affiliation: Laboratório de Bioinorgânica e Crystalografia, Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brazil.
authors.forename: Maryene A
authors.initials: MA
authors.lastname: Camargo
authors.forename: Ademir
authors.initials: A
authors.lastname: Neves
authors.forename: Bruno
authors.initials: B
authors.lastname: Szpoganicz
authors.forename: Adailton J
authors.initials: AJ
authors.lastname: Bortoluzzi
authors.forename: Franciele L
authors.initials: FL
authors.lastname: Fischer
authors.forename: Hernán
authors.initials: H
authors.lastname: Terenzi
authors.forename: Eduardo E
authors.initials: EE
authors.lastname: Castellano
mesh_terms: D003851:Deoxyribonucleases / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared
chemical_list: D008024:Ligands; D005682:Gadolinium; D003851:Deoxyribonucleases; D010744:Phosphoric Monoester Hydrolases