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Litke JL, Li Y, Nocka LM, Mukerji I. Probing the Ion Binding Site in a DNA Holliday Junction Using Förster Resonance Energy Transfer (FRET). Int J Mol Sci 2016; 17:366. [PMID: 26978349 PMCID: PMC4813226 DOI: 10.3390/ijms17030366] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/21/2016] [Accepted: 02/26/2016] [Indexed: 11/17/2022] Open
Abstract
Holliday Junctions are critical DNA intermediates central to double strand break repair and homologous recombination. The junctions can adopt two general forms: open and stacked-X, which are induced by protein or ion binding. In this work, fluorescence spectroscopy, metal ion luminescence and thermodynamic measurements are used to elucidate the ion binding site and the mechanism of junction conformational change. Förster resonance energy transfer measurements of end-labeled junctions monitored junction conformation and ion binding affinity, and reported higher affinities for multi-valent ions. Thermodynamic measurements provided evidence for two classes of binding sites. The higher affinity ion-binding interaction is an enthalpy driven process with an apparent stoichiometry of 2.1 ± 0.2. As revealed by Eu(3+) luminescence, this binding class is homogeneous, and results in slight dehydration of the ion with one direct coordination site to the junction. Luminescence resonance energy transfer experiments confirmed the presence of two ions and indicated they are 6-7 Å apart. These findings are in good agreement with previous molecular dynamics simulations, which identified two symmetrical regions of high ion density in the center of stacked junctions. These results support a model in which site-specific binding of two ions in close proximity is required for folding of DNA Holliday junctions into the stacked-X conformation.
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Affiliation(s)
- Jacob L Litke
- Department of Molecular Biology and Biochemistry and Molecular Biophysics Program, Wesleyan University, Middletown, CT 06459-0175, USA.
| | - Yan Li
- Department of Molecular Biology and Biochemistry and Molecular Biophysics Program, Wesleyan University, Middletown, CT 06459-0175, USA.
| | - Laura M Nocka
- Department of Molecular Biology and Biochemistry and Molecular Biophysics Program, Wesleyan University, Middletown, CT 06459-0175, USA.
| | - Ishita Mukerji
- Department of Molecular Biology and Biochemistry and Molecular Biophysics Program, Wesleyan University, Middletown, CT 06459-0175, USA.
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Law GL, Andolina CM, Xu J, Luu V, Rutkowski PX, Muller G, Shuh DK, Gibson JK, Raymond KN. Circularly polarized luminescence of curium: a new characterization of the 5f actinide complexes. J Am Chem Soc 2012; 134:15545-9. [PMID: 22920726 DOI: 10.1021/ja306354n] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A key distinction between the lanthanide (4f) and the actinide (5f) transition elements is the increased role of f-orbital covalent bonding in the latter. Circularly polarized luminescence (CPL) is an uncommon but powerful spectroscopy which probes the electronic structure of chiral, luminescent complexes or molecules. While there are many examples of CPL spectra for the lanthanides, this report is the first for an actinide. Two chiral, octadentate chelating ligands based on orthoamide phenol (IAM) were used to complex curium(III). While the radioactivity kept the amount of material limited to micromole amounts, spectra of the highly luminescent complexes showed significant emission peak shifts between the different complexes, consistent with ligand field effects previously observed in luminescence spectra.
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Affiliation(s)
- Ga-Lai Law
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
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Burton-Pye BP, Jones I, Cutler CS, Howell RC, Francesconi LC. Investigation into the extraction speciation of rare-earth radioisotopes from aqueous solution using polyoxometalates. Inorganica Chim Acta 2012. [DOI: 10.1016/j.ica.2011.09.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Dissanayake P, Mei Y, Allen MJ. Luminescence-Decay as an Easy-to-Use Tool for the Study of Lanthanide-Containing Catalysts in Aqueous Solutions. ACS Catal 2011. [DOI: 10.1021/cs200213a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Prabani Dissanayake
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Yujiang Mei
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Matthew J. Allen
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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Hammell J, Buttarazzi L, Huang CH, Morrow JR. Eu(III) complexes as anion-responsive luminescent sensors and paramagnetic chemical exchange saturation transfer agents. Inorg Chem 2011; 50:4857-67. [PMID: 21548563 PMCID: PMC3528016 DOI: 10.1021/ic200075w] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Eu(III) complex of (1S,4S,7S,10S)-1,4,7,10-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane (S-THP) is studied as a sensor for biologically relevant anions. Anion interactions produce changes in the luminescence emission spectrum of the Eu(III) complex, in the (1)H NMR spectrum, and correspondingly, in the PARACEST spectrum of the complex (PARACEST = paramagnetic chemical exchange saturation transfer). Direct excitation spectroscopy and luminescence lifetime studies of Eu(S-THP) give information about the speciation and nature of anion interactions including carbonate, acetate, lactate, citrate, phosphate, and methylphosphate at pH 7.2. Data is consistent with the formation of both innersphere and outersphere complexes of Eu(S-THP) with acetate, lactate, and carbonate. These anions have weak dissociation constants that range from 19 to 38 mM. Citrate binding to Eu(S-THP) is predominantly innersphere with a dissociation constant of 17 μM. Luminescence emission peak changes upon addition of anion to Eu(S-THP) show that there are two distinct binding events for phosphate and methylphosphate with dissociation constants of 0.3 mM and 3.0 mM for phosphate and 0.6 mM and 9.8 mM for methyl phosphate. Eu(THPC) contains an appended carbostyril derivative as an antenna to sensitize Eu(III) luminescence. Eu(THPC) binds phosphate and citrate with dissociation constants that are 10-fold less than that of the Eu(S-THP) parent, suggesting that functionalization through a pendent group disrupts the anion binding site. Eu(S-THP) functions as an anion responsive PARACEST agent through exchange of the alcohol protons with bulk water. The alcohol proton resonances of Eu(S-THP) shift downfield in the presence of acetate, lactate, citrate, and methylphosphate, giving rise to distinct PARACEST peaks. In contrast, phosphate binds to Eu(S-THP) to suppress the PARACEST alcohol OH peak and carbonate does not markedly change the alcohol peak at 5 mM Eu(S-THP), 15 mM carbonate at pH 6.5 or 7.2. This work shows that the Eu(S-THP) complex has unique selectivity toward binding of biologically relevant anions and that anion binding results in changes in both the luminescence and the PARACEST spectra of the complex.
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Affiliation(s)
- Jacob Hammell
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000
| | - Leandro Buttarazzi
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000
| | - Ching-Hui Huang
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000
| | - Janet R. Morrow
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260-3000
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Burton-Pye BP, Francesconi LC. Speciation of organic-soluble europium(iii) α1-Wells–Dawson complexes. Dalton Trans 2011; 40:4421-33. [DOI: 10.1039/c0dt01309a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Andolina CM, Morrow JR. Luminescence Resonance Energy Transfer in Heterodinuclear LnIII Complexes for Sensing Biologically Relevant Anions. Eur J Inorg Chem 2010. [DOI: 10.1002/ejic.201000779] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Huang CH, Hammell J, Ratnakar SJ, Sherry AD, Morrow JR. Activation of a PARACEST agent for MRI through selective outersphere interactions with phosphate diesters. Inorg Chem 2010; 49:5963-70. [PMID: 20509631 PMCID: PMC2893239 DOI: 10.1021/ic1004616] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ln(S-THP)(3+) complexes are paramagnetic chemical exchange saturation transfer (PARACEST) agents for magnetic resonance imaging (MRI; S-THP = (1S,4S,7S,10S)-1,4,7,10-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane, Ln(III) = Ce(III), Eu(III), Yb(III)). CEST spectra at 11.7 T show that the PARACEST effect of these complexes is enhanced at neutral pH in buffered solutions containing 100 mM NaCl upon the addition of 1-2 equiv of diethylphosphate (DEP). CEST images of phantoms at 4.7 T confirm that DEP enhances the properties of Yb(S-THP)(3+) as a PARACEST MRI agent in buffered solutions at neutral pH and 100 mM NaCl. Studies using (1)H NMR, direct excitation Eu(III) luminescence spectroscopy, and UV-visible spectroscopy show that DEP is an outersphere ligand. Dissociation constants for [Ln(S-THP)(OH(2))](DEP) are 1.9 mM and 2.8 mM for Ln(III) = Yb(III) at pH 7.0 and Eu(III) at pH 7.4. Related ligands including phosphorothioic acid, O,O-diethylester, ethyl methylphosphonate, O-(4-nitrophenylphosphoryl)choline, and cyclic 3,5-adenosine monophosphate do not activate PARACEST. BNPP (bis(4-nitrophenyl phosphate) activates PARACEST of Ln(S-THP)(3+) (Ln(III) = Eu(III), Yb(III)), albeit less effectively than does DEP. These data show that binding through second coordination sphere interactions is selective for phosphate diesters with two terminal oxygens and two identical ester groups. A crystal structure of [Eu(S-THP)(OH(2))]((O(2)NPhO)(2)PO(2))(2)(CF(3)SO(3)) x 2 H(2)O x iPrOH has two outersphere BNPP anions that form hydrogen bonds to the alcohol groups of the macrocycle and the bound water ligand. This structure supports (1)H NMR spectroscopy studies showing that outersphere interactions of the phosphate diester with the alcohol protons modulate the rate of alcohol proton exchange to influence the PARACEST properties of the complex. Further, DEP interacts only with the nonionized form of the complex, Ln(S-THP)(OH(2))(3+) contributing to the pH dependence of the PARACEST effect.
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Affiliation(s)
- Ching-Hui Huang
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260, Fax (1)716-645-6963
| | - Jacob Hammell
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260, Fax (1)716-645-6963
| | - S. James Ratnakar
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 2201 Inwood Road, Dallas, TX 75390-8568
| | - A. Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 2201 Inwood Road, Dallas, TX 75390-8568
- Department of Chemistry, University of Texas, Dallas, P.O. Box 830688, Richardon, TX 75083-0688, Fax (1) 972-883-2025
| | - Janet R. Morrow
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260, Fax (1)716-645-6963
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Huang CH, Parish A, Samain F, Garo F, Häner R, Morrow JR. Binding of Europium(III) to a Non-Nucleosidic Phenanthroline Linker in DNA. Bioconjug Chem 2010; 21:476-82. [DOI: 10.1021/bc900386w] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Ching-Hui Huang
- Department of Chemistry, 526 Natural Sciences Complex, University at Buffalo, State University of New York, Amherst, New York 14260-3000, and Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Austin Parish
- Department of Chemistry, 526 Natural Sciences Complex, University at Buffalo, State University of New York, Amherst, New York 14260-3000, and Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Florent Samain
- Department of Chemistry, 526 Natural Sciences Complex, University at Buffalo, State University of New York, Amherst, New York 14260-3000, and Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Florian Garo
- Department of Chemistry, 526 Natural Sciences Complex, University at Buffalo, State University of New York, Amherst, New York 14260-3000, and Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Robert Häner
- Department of Chemistry, 526 Natural Sciences Complex, University at Buffalo, State University of New York, Amherst, New York 14260-3000, and Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Janet R. Morrow
- Department of Chemistry, 526 Natural Sciences Complex, University at Buffalo, State University of New York, Amherst, New York 14260-3000, and Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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Sánchez-Lombardo I, Andolina CM, Morrow JR, Yatsimirsky AK. Speciation of Eu(iii) hydroxo complexes in aqueous DMSO studied by direct excitation luminescence spectroscopy and their catalytic activity in phosphodiester cleavage. Dalton Trans 2010; 39:864-73. [DOI: 10.1039/b918722g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Andolina C, Mathews R, Morrow J. Solution Chemistry of Europium(III) Aqua Ion at Micromolar Concentrations as Probed by Direct Excitation Luminescence Spectroscopy. Helv Chim Acta 2009. [DOI: 10.1002/hlca.200900166] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Nwe K, Andolina CM, Huang CH, Morrow JR. PARACEST properties of a dinuclear neodymium(III) complex bound to DNA or carbonate. Bioconjug Chem 2009; 20:1375-82. [PMID: 19555071 DOI: 10.1021/bc900146z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A dinuclear Nd(III) macrocyclic complex of 1 (1,4-bis[1-(4,7,10-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane]-p-xylene) and mononuclear complexes of 1,4,7-tris-1,4,7,10-tetraazacyclododecane, 2, and 1,4,7-tris[(N-N-diethyl)carbamoylmethyl]-1,4,7,10-tetraazacyclododecane, 3, are prepared. Complexes of 1 and 2 give rise to a PARACEST (paramagnetic chemical exchange saturation transfer) peak from exchangeable amide protons that resonate approximately 12 ppm downfield from the bulk water proton resonance. The dinuclear Nd(III) complex is promising as a PARACEST contrast agent for MRI applications, because it has an optimal pH of 7.5 and the rate constant for amide proton exchange (2700 s(-1)) is nearly as large as it can be within slow exchange conditions with bulk water. Dinuclear Ln(2)(1) complexes (Ln(III) = Nd(III), Eu(III)) bind tightly to anionic ligands including carbonate, diethyl phosphate, and DNA. The CEST amide peak of Nd(2)(1) is enhanced by certain DNA sequences that contain hairpin loops, but decreases in the presence of diethyl phosphate or carbonate. Direct excitation luminescence studies of Eu(2)(1) show that double-stranded and hairpin-loop DNA sequences displace one water ligand on each Eu(III) center. DNA displaces carbonate ion despite the low dissociation constant for the Eu(2)(1) carbonate complex (K(d) = 15 microM). Enhancement of the CEST effect of a lanthanide complex by binding to DNA is a promising step toward the preparation of PARACEST agents containing DNA scaffolds.
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Affiliation(s)
- Kido Nwe
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
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Escudier JM, Dupouy C, Fountain MA, del Mundo IMA, Jacklin EM, Morrow JR. Synthesis and luminescence properties of a trinucleotide-europium(III) complex conjugate. Org Biomol Chem 2009; 7:3251-7. [PMID: 19641782 DOI: 10.1039/b902643f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two trinucleotide conjugates of the macrocyclic ligand 1,4,7-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane are prepared. One contains only DNA (1) and the second is a chimeric RNA/DNA conjugate (2). The synthetic methodology used to prepare the trinucleotide macrocyclic ligand conjugates is based on the introduction of a convertible nucleoside which has an electrophilic function to facilitate the attachment of any nucleophilic ligand to the 5-position of the 3-nucleoside unit. The convertible nucleoside is first treated with the macrocyclic ligand, 1,4,7,10-tetraazacyclododecane, followed by alkylation of the three remaining amine groups to give a conjugated macrocyclic ligand with three pendent amide groups. Addition of an equivalent of EuCl3 to trinucleotide (1) or (2) yields the complexes Eu(1) and Eu(2), respectively. Studies using time-resolved and steady state direct excitation luminescence spectroscopy show that Eu(III) binds to the macrocyclic moiety in 1 and in 2. The excitation peak frequency for the 7Fo5Do transition and the unexpectedly low number of water ligands in Eu(1) and Eu(2) are consistent with additional interactions of the Eu(III) macrocycle with one of the phosphate diester groups. Studies show that Eu(2) undergoes cleavage at the uridine nucleotide. The unique point of attachment of the macrocyclic complex will enable the preparation of new lanthanide nucleic acid conjugates with useful properties.
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Affiliation(s)
- Jean-Marc Escudier
- Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 4, France.
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