1
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Jones NC, Rodger A, Hoffmann SV. Advantages of a synchrotron light source for fluorescence-detected linear dichroism. Chirality 2024; 36:e23667. [PMID: 38607651 DOI: 10.1002/chir.23667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 02/26/2024] [Accepted: 03/14/2024] [Indexed: 04/13/2024]
Abstract
Fluorescence-detected linear dichroism (FD-LD) enables one to collect linear dichroism spectra for oriented fluorophores in the presence of other absorbing species and light scattering. The experiment proceeds by scanning the excitation wavelength and using a filter to collect only emitted photons from the fluorophore. Thus, it has the potential to give data with enhanced selectivity and quality. By using a synchrotron radiation light source and fluorescence-detection, we show data for a range of fluorophores in different orienting environments. Film and flow-oriented FD-LD spectra were collected down to 170 nm. Even for flow-oriented liposomes, we have data collected down to 210 nm. For strongly scattering samples, for example, liposomes, FD-LD has the clear advantage that scattering is absent for the longer wavelength fluorescence photons. The collimated and smaller beam size of the synchrotron radiation also gives rise to sharper and more well-defined features in the spectra.
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Affiliation(s)
- Nykola C Jones
- ISA, Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Alison Rodger
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Søren V Hoffmann
- ISA, Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
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2
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Flow Linear Dichroism of Protein-Membrane Systems. Methods Mol Biol 2021. [PMID: 33877612 DOI: 10.1007/978-1-0716-1197-5_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2023]
Abstract
Linear dichroism (LD) is the differential absorbance of light polarized parallel and perpendicular to an orientation direction. Any oriented sample will show a signal in its electronic as well as vibrational transitions. Model membrane small unilamellar vesicles or liposomes provide an oriented system when they are subject to shear flow in a Couette or other type of flow cell. Anything, including peptides and proteins, that is bound to the liposome also gives an LD signal whereas unbound analytes are invisible. Flow LD is the ideal technique for determining the orientation of different chromophores with respect to the membrane normal. To illustrate the power of the method, data for diphenyl hexatriene, fluorene, antimicrobial peptides (aurein 2.5 and gramicidin), are considered as well as another common chromophore, fluorene, often used to increase the hydrophobicity and hence membrane binding of peptides. How LD can be used both for geometry, structure analysis and probing kinetic processes is considered. Kinetic analysis usually involves identifying binding (appearance of an LD signal), insertion (sign change), often followed by loss of signal, if the inserted protein or peptide disrupts the membrane .
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3
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Lizio MG, Campana M, De Poli M, Jefferies DF, Cullen W, Andrushchenko V, Chmel NP, Bouř P, Khalid S, Clayden J, Blanch E, Rodger A, Webb SJ. Insight into the Mechanism of Action and Peptide-Membrane Interactions of Aib-Rich Peptides: Multitechnique Experimental and Theoretical Analysis. Chembiochem 2021; 22:1656-1667. [PMID: 33411956 PMCID: PMC8248331 DOI: 10.1002/cbic.202000834] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 01/06/2021] [Indexed: 12/16/2022]
Abstract
The increase in resistant bacterial strains necessitates the identification of new antimicrobial molecules. Antimicrobial peptides (AMPs) are an attractive option because of evidence that bacteria cannot easily develop resistance to AMPs. The peptaibols, a class of naturally occurring AMPs, have shown particular promise as antimicrobial drugs, but their development has been hindered by their mechanism of action not being clearly understood. To explore how peptaibols might interact with membranes, circular dichroism, vibrational circular dichroism, linear dichroism, Raman spectroscopy, Raman optical activity, neutron reflectivity and molecular dynamics simulations have been used to study a small library of peptaibol mimics, the Aib-rich peptides. All the peptides studied quickly partitioned and oriented in membranes, and we found evidence of chiral interactions between the phospholipids and membrane-embedded peptides. The protocols presented in this paper open new ground by showing how chiro-optical spectroscopies can throw light on the mechanism of action of AMPs.
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Affiliation(s)
| | - Mario Campana
- ISIS Neutron and Muon SourceRutherford Appleton Laboratory Harwell DidcotOxfordOX11 0QXUK
| | - Matteo De Poli
- Department of ChemistryUniversity of ManchesterOxford RoadManchesterM13 9PLUK
| | | | - William Cullen
- Department of ChemistryUniversity of ManchesterOxford RoadManchesterM13 9PLUK
- Manchester Institute of BiotechnologyUniversity of Manchester131 Princess St.ManchesterM1 7DNUK
| | - Valery Andrushchenko
- Institute of Organic Chemistry and BiochemistryAcademy of SciencesFlemingovo náměstí 216610Prague 6Czech Republic
| | - Nikola P. Chmel
- Department of ChemistryUniversity of WarwickCoventryCV4 7ALUK
| | - Petr Bouř
- Institute of Organic Chemistry and BiochemistryAcademy of SciencesFlemingovo náměstí 216610Prague 6Czech Republic
| | - Syma Khalid
- School of ChemistryUniversity of Southampton HighfieldSouthamptonSO17 1BJUK
| | - Jonathan Clayden
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Ewan Blanch
- School of ScienceRMIT UniversityGPO Box 2476MelbourneVictoria3001Australia
| | - Alison Rodger
- Department of ChemistryUniversity of WarwickCoventryCV4 7ALUK
- Department of Molecular SciencesMacquarie UniversitySydneyNSW 2109Australia
| | - Simon J. Webb
- Department of ChemistryUniversity of ManchesterOxford RoadManchesterM13 9PLUK
- Manchester Institute of BiotechnologyUniversity of Manchester131 Princess St.ManchesterM1 7DNUK
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4
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Gekko K. Synchrotron-radiation vacuum-ultraviolet circular dichroism spectroscopy in structural biology: an overview. Biophys Physicobiol 2019; 16:41-58. [PMID: 30923662 PMCID: PMC6435020 DOI: 10.2142/biophysico.16.0_41] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 01/13/2019] [Indexed: 12/01/2022] Open
Abstract
Circular dichroism spectroscopy is widely used for analyzing the structures of chiral molecules, including biomolecules. Vacuum-ultraviolet circular dichroism (VUVCD) spectroscopy using synchrotron radiation can extend the short-wavelength limit into the vacuum-ultraviolet region (down to ~160 nm) to provide detailed and new information about the structures of biomolecules in combination with theoretical analysis and bioinformatics. The VUVCD spectra of saccharides can detect the high-energy transitions of chromophores such as hydroxy and acetal groups, disclosing the contributions of inter- or intramolecular hydrogen bonds to the equilibrium configuration of monosaccharides in aqueous solution. The roles of hydration in the fluctuation of the dihedral angles of carboxyl and amino groups of amino acids can be clarified by comparing the observed VUVCD spectra with those calculated theoretically. The VUVCD spectra of proteins markedly improves the accuracy of predicting the contents and number of segments of the secondary structures, and their amino acid sequences when combined with bioinformatics, for not only native but also nonnative and membrane-bound proteins. The VUVCD spectra of nucleic acids confirm the contributions of the base composition and sequence to the conformation in comparative analyses of synthetic poly-nucleotides composed of selected bases. This review surveys these recent applications of synchrotron-radiation VUVCD spectroscopy in structural biology, covering saccharides, amino acids, proteins, and nucleic acids.
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Affiliation(s)
- Kunihiko Gekko
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan
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5
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Rodger A, Dorrington G, Ang DL. Linear dichroism as a probe of molecular structure and interactions. Analyst 2018; 141:6490-6498. [PMID: 27840872 DOI: 10.1039/c6an01771a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Linear dichroism (LD) spectroscopy involves measuring the wavelength (or energy) dependence of the difference in absorption of light parallel and perpendicular to an orientation direction. It requires samples to have a net orientation. The aim of this review is to summarise some UV-visible linear dichroism (LD) methods that can be usefully applied to increase our understanding of biomacromolecules and their complexes that have a high aspect ratio. LD shares the advantages of most spectroscopic techniques including the fact that data collection is fairly straightforward and many sample types can be investigated. Conversely, LD shares the disadvantage that the measured signal is an average over all species in the sample on which the light beam is incident. LD mitigates this disadvantage somewhat in that only species which are oriented give a net signal. How the data can be analysed to give structural information about small molecules in stretched films and membrane systems or bound to biomacromolecules and directly about biomacromolecules such as DNA and protein fibres forms part of this review. In the UV-visible region LD often suffers noticeably from light scattering since the samples tend to be large relative to the wavelength of the incident light, so consideration is also given to data analysis challenges including removal of scattering contributions to an observed signal. Brief mention is made of fluorescence detected LD.
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Affiliation(s)
- Alison Rodger
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - Glen Dorrington
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - Dale L Ang
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
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6
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Razmkhah K, Chmel NP, Gibson MI, Rodger A. Oxidized polyethylene films for orienting polar molecules for linear dichroism spectroscopy. Analyst 2015; 139:1372-82. [PMID: 24482800 DOI: 10.1039/c3an02322b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Stretched polyethylene (PE) films have been used to orient small molecules for decades by depositing solutions on their surface and allowing the solvent to evaporate leaving the analyte absorbed on the polymer film. However, the non-polar hydrophobic nature of PE is an obstacle to aligning polar molecules and biological samples. In this work PE film was treated with oxygen plasma in order to increase surface hydrophilicity. Different treatment conditions were evaluated using contact angle measurement and X-ray photoelectron spectroscopy. Treated PE (PE(OX)) films are shown to be able to align molecules of different polarities including progesterone, 1-pyrenecarboxaldehyde, 4',6-diamidino-2-phenylindole (DAPI) and anthracene. The degree of alignment of each molecule was studied by running series of linear dichroism (LD) experiments and the polarizations of electronic transition moments were determined. For the first time optimal conditions (such as stretching factor and concentration of the sample) for stretched film LD were determined. PE(OX) aligning ability was compared to that of normal PE films. Progesterone showed a slightly better alignment on PE(OX) than PE. 1-Pyrenecarboxaldehyde oriented differently on the two different films which enabled transition moment assignment for this low symmetry molecule. DAPI (which does not align on PE) aligned well on PE(OX) and enabled us to obtain better LD data than had previously been collected with polyvinyl alcohol. Anthracene alignment and formation of dimers and higher order structures were studied in much more detail than previously possible, showing a variety of assemblies on PE and PE(OX) films.
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Affiliation(s)
- Kasra Razmkhah
- Department of Chemistry and Warwick Analytical Science Centre, University of Warwick, Coventry, CV4 7AL, UK.
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7
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Role of liposome and peptide in the synergistic enhancement of transfection with a lipopolyplex vector. Sci Rep 2015; 5:9292. [PMID: 25786833 PMCID: PMC4365389 DOI: 10.1038/srep09292] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Accepted: 02/26/2015] [Indexed: 01/22/2023] Open
Abstract
Lipopolyplexes are of widespread interest for gene therapy due to their multifunctionality and high transfection efficiencies. Here we compared the biological and biophysical properties of a lipopolyplex formulation with its lipoplex and polyplex equivalents to assess the role of the lipid and peptide components in the formation and function of the lipopolyplex formulation. We show that peptide efficiently packaged plasmid DNA forming spherical, highly cationic nanocomplexes that are taken up efficiently by cells. However, transgene expression was poor, most likely due to endosomal degradation since the polyplex lacks membrane trafficking properties. In addition the strong peptide-DNA interaction may prevent plasmid release from the complex and so limit plasmid DNA availability. Lipid/DNA lipoplexes, on the other hand, produced aggregated masses that showed poorer cellular uptake than the polyplex but contrastingly greater levels of transgene expression. This may be due to the greater ability of lipoplexes relative to polyplexes to promote endosomal escape. Lipopolyplex formulations formed spherical, cationic nanocomplexes with efficient cellular uptake and significantly enhanced transfection efficiency. The lipopolyplexes combined the optimal features of lipoplexes and polyplexes showing optimal cell uptake, endosomal escape and availability of plasmid for transcription, thus explaining the synergistic increase in transfection efficiency.
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8
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Kogan M, Nordén B, Beke-Somfai T. High anisotropy of flow-aligned bicellar membrane systems. Chem Phys Lipids 2013; 175-176:105-15. [PMID: 23999012 DOI: 10.1016/j.chemphyslip.2013.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 08/17/2013] [Accepted: 08/19/2013] [Indexed: 10/26/2022]
Abstract
In recent years, multi-lipid bicellar systems have emerged as promising membrane models. The fast orientational diffusion and magnetic alignability made these systems very attractive for NMR investigations. However, their alignment was so far achieved with a strong magnetic field, which limited their use with other methods that require macroscopic orientation. Recently, it was shown that bicelles could be aligned also by shear flow in a Couette flow cell, making it applicable to structural and biophysical studies by polarized light spectroscopy. Considering the sensitivity of this lipid system to small variations in composition and physicochemical parameters, efficient use of such a flow-cell method with coupled techniques will critically depend on the detailed understanding of how the lipid systems behave under flow conditions. In the present study we have characterized the flow alignment behavior of the commonly used dimyristoyl phosphatidylcholine/dicaproyl phosphatidylcholine (DMPC/DHPC) bicelle system, for various temperatures, lipid compositions, and lipid concentrations. We conclude that at optimal flow conditions the selected bicellar systems can produce the most efficient flow alignment out of any lipid systems used so far. The highest degree of orientation of DMPC/DHPC samples is noticed in a narrow temperature interval, at a practical temperature around 25 °C, most likely in the phase transition region characterized by maximum sample viscosity. The change of macroscopic orientation factor as function of the above conditions is now described in detail. The increase in macroscopic alignment observed for bicelles will most likely allow recording of higher resolution spectra on membrane systems, which provide deeper structural insight and analysis into properties of biomolecules interacting with solution phase lipid membranes.
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Affiliation(s)
- Maxim Kogan
- Department of Chemical and Biological Engineering, Physical Chemistry, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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9
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Daviter T, Chmel N, Rodger A. Circular and linear dichroism spectroscopy for the study of protein-ligand interactions. Methods Mol Biol 2013; 1008:211-241. [PMID: 23729254 DOI: 10.1007/978-1-62703-398-5_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Circular dichroism (CD) is the difference in absorption of left and right circularly polarized light, usually by a solution containing the molecules of interest. A non-zero signal for solutions is only measured for chiral molecules such as proteins whose mirror image is not superposable on the original molecule. A CD spectrum provides information about the bonds and structures responsible for the chirality. When a small molecule (or ligand) binds to a protein, it acquires an induced CD (ICD) spectrum through chiral perturbation to its structure or electron rearrangements (transitions). The wavelengths of this ICD are determined by the ligand's own absorption spectrum, and the intensity of the ICD spectrum is determined by the strength and geometry of its interaction with the protein. Thus, ICD can be used to probe the binding of ligands to proteins. This chapter contains an outline of how to perform protein CD and ICD experiments, together with some of the issues relating to experimental design and implementation. Addition of a quarter wave plate to a CD spectropolarimeter converts it to a linear dichroism (LD) spectrometer. When protein samples are aligned either in flow (as for fibers or membrane proteins in liposomes) or on surfaces the orientations of ligands with respect to the protein backbone or other subunits can be determined.
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Affiliation(s)
- Tina Daviter
- ISMB Biophysics Centre, Institute of Structural and Molecular Biology, Birkbeck, University of London, London, UK
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10
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Hicks MR, Rodger A, Lin YP, Jones NC, Hoffmann SV, Dafforn TR. Rapid Injection Linear Dichroism for Studying the Kinetics of Biological Processes. Anal Chem 2012; 84:6561-6. [DOI: 10.1021/ac300842h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Matthew R. Hicks
- Department of Chemistry and
Warwick Centre for Analytical Science, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Alison Rodger
- Department of Chemistry and
Warwick Centre for Analytical Science, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Yu-pin Lin
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, United
Kingdom
| | - Nykola C. Jones
- Institute for Storage
Ring Facilities
(ISA), Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Søren Vrønning Hoffmann
- Institute for Storage
Ring Facilities
(ISA), Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Timothy R. Dafforn
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, United
Kingdom
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11
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Saaka Y, Deller RC, Rodger A, Gibson MI. Exploiting Thermoresponsive Polymers to Modulate Lipophilicity: Interactions With Model Membranes. Macromol Rapid Commun 2012; 33:779-84. [DOI: 10.1002/marc.201100873] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 01/24/2012] [Indexed: 01/21/2023]
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12
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Cerasoli E, Ravi J, Gregor C, Hussain R, Siligardi G, Martyna G, Crain J, Ryadnov MG. Membrane mediated regulation in free peptides of HIV-1 gp41: minimal modulation of the hemifusion phase. Phys Chem Chem Phys 2012; 14:1277-85. [DOI: 10.1039/c1cp23155c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Is photocleavage of DNA by YOYO-1 using a synchrotron radiation light source sequence dependent? EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 40:1121-9. [PMID: 21931957 DOI: 10.1007/s00249-011-0739-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 07/21/2011] [Accepted: 07/26/2011] [Indexed: 10/17/2022]
Abstract
The photocleavage of double-stranded and single-stranded DNA by the fluorescent dye YOYO-1 was investigated in real time by using the synchrotron radiation light source ASTRID (ISA, Denmark) both to initiate the reaction and to monitor its progress using Couette flow linear dichroism (LD) throughout the irradiation period. The dependence of LD signals on DNA sequences and on time in the intense light beam was explored and quantified for single-stranded poly(dA), poly[(dA-dT)(2)], calf thymus DNA (ctDNA) and Micrococcus luteus DNA (mlDNA). The DNA and ligand regions of the spectrum showed different LD kinetic behaviors, and there was significant sequence dependence of the kinetics. However, in contrast to expectations from the literature, we found that poly(dA), mlDNA, low salt ctDNA and low salt poly[(dA-dT)(2)] all had significant populations of groove-bound YOYO. It seems that this mode was predominantly responsible for the catalysis of DNA cleavage. In homopolymeric DNAs, intercalated YOYO was unable to cleave DNA. In mixed-sequence DNAs the data suggest that YOYO in some but not all intercalated binding sites can cause cleavage. It is also likely that cleavage occurs at transient single-stranded regions. The reaction rates for a 100 mA beam current of 0.5-μW power varied from 0.6 h(-1) for single-stranded poly(dA) to essentially zero for low salt poly[(dG-dC)(2)] and high salt poly[(dA-dT)(2)]. At the conclusion of the experiments with each kind of DNA, uncleaved DNA with intercalated YOYO remained.
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14
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Lamarre B, Ravi J, Ryadnov MG. GeT peptides: a single-domain approach to gene delivery. Chem Commun (Camb) 2011; 47:9045-7. [DOI: 10.1039/c1cc13043a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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15
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Hicks MR, Kowałski J, Rodger A. LD spectroscopy of natural and synthetic biomaterials. Chem Soc Rev 2010; 39:3380-93. [DOI: 10.1039/b912917k] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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16
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Rittman M, Gilroy E, Koohy H, Rodger A, Richards A. Is DNA a worm-like chain in Couette flow? In search of persistence length, a critical review. Sci Prog 2009; 92:163-204. [PMID: 19697713 PMCID: PMC10361128 DOI: 10.3184/003685009x462205] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Persistence length is the foremost measure of DNA flexibility. Its origins lie in polymer theory which was adapted for DNA following the determination of BDNA structure in 1953. There is no single definition of persistence length used, and the links between published definitions are based on assumptions which may, or may not be, clearly stated. DNA flexibility is affected by local ionic strength, solvent environment, bound ligands and intrinsic sequence-dependent flexibility. This article is a review of persistence length providing a mathematical treatment of the relationships between four definitions of persistence length, including: correlation, Kuhn length, bending, and curvature. Persistence length has been measured using various microscopy, force extension and solution methods such as linear dichroism and transient electric birefringence. For each experimental method a model of DNA is required to interpret the data. The importance of understanding the underlying models, along with the assumptions required by each definition to determine a value of persistence length, is highlighted for linear dichroism data, where it transpires that no model is currently available for long DNA or medium to high shear rate experiments.
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Affiliation(s)
- Martyn Rittman
- Molecular Organisation and Assembly in Cells Doctoral Training Centre
| | - Emma Gilroy
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Hashem Koohy
- Molecular Organisation and Assembly in Cells Doctoral Training Centre
| | - Alison Rodger
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Adair Richards
- Molecular Organisation and Assembly in Cells Doctoral Training Centre
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