Fluorescence-detected Circular Dichroism Research Articles

Novel instrument for measurement of multidimensional fluorescence detected circular dichroism

A new microprocessor-controlled multichannel spectrometer for the measurement of fluorescence detected circular dichroism (FDCD) is presented. Spectra of model steroid compounds are provided to demonstrate the analytical utility of multichannel FDCD over the classical circular dichroism measurement. A detection limit of 3.05×10−8 M was determined for a solution of estrone based on a signal/noise ratio of 2 as a lower limit. The optics and electronics for the rapid acquisition of multichannel FDCD data are described in detail.

Fluorescence-detected circular dichroism of ethidium bound to nucleic acids

Fluorescence-detected circular dichroism of ethidium bound to nucleic acids

Fluorescence-detected circular dichroism of ethidium bound to poly(dG-dC) and poly(dG-m5dC) under B- and Z-form conditions.

The equilibrium binding of ethidium to poly(dG-dC) and poly(dG-m5dC) under conditions favoring B and Z forms was investigated with fluorescence-detected circular dichroism (FDCD) and optical titration methods. FDCD spectra indicate a similar geometry for the intercalated ethidium under both B- and Z-form conditions, even at low levels of bound ethidium. The magnitude of the 310-330-nm FDCD band as a function of the bound drug to base pair ratio (r) indicates ethidium binds to poly(dG-dC) in 4.4 M NaCl and to poly(dG-m5dC) in 25 mM MgCl2 by clustering. Under these conditions, circular dichroism spectra indicate the polymer is largely Z form. Thus, it appears ethidium clusters into regions it has induced into a right-handed form. For all conditions studied, the FDCD spectra provided no evidence for a left-handed binding site. Under B-form conditions, binding is random.

One-Dimensional Aromatic Crystals in Solution VI. Synthesis and Spectroscopic Characterization of Poly(β-9-anthrylmethyl L-aspartate)

An aromatic poly(α-amino acid) carrying anthryl chromophores, poly(9-anthrylmethyl L-aspartate), was first synthesized in a form of a block copolymer with poly(γ-benzyl DL-glutamate) which functions as a solubilizing component. The polypeptide in trimethyl phosphate solution showed a marked exciton splitting in the circular dichroism at the 1Bb absorption band, indicating a helical arrangement of anthryl groups along the helical main chain. Electronic interactions in the ground and excited states of the aromatic polypeptide were studied by absorption, fluorescence, circular dichroism (CD), circularly polarized fluorescence (CPF), and fluorescence-detected circular dichroism (FDCD) spectroscopy. In the ground state, some portion of the anthryl groups was found to form dimers or higher aggregates. The fluorescence spectra of the polymer consisted of monomer fluorescence with a small contribution of the dimer excited state. The CPF spectrum indicated that the monomer excited state partially delocalizes over neighboring anthryl groups. The dimer emission also showed a significant circular polarization, indicating dissymmetric structure of the dimer. The FDCD spectrum, when monitored by the dimer fluorescence, showed a more intense CD signal than that of conventional absorption CD, indicating that the dimer is formed in a helical part of the polypeptide. On the basis of these observations, a scheme was proposed for the electronic states of the anthryl polypeptide.

Strategies for the Reduction and Interpretation of Multicomponent Spectral Data.

Fluorescence data can be rapidly acquired in the form of an emission-excitation matrix (EEM) using a novel fluorometer called a video fluorometer (VF). An EEM array of 4096 data points composed of fluorescence intensity measured at 64 different emission wavelengths and excited at 64 different excitation wavelengths can be acquired in less than one second. The time-limiting factor in using this information for analytical measurement is the interpretation step. Consequently, sophisticated computer algorithms must be developed to aid in interpretation of such large data sets. For "r" number of components, the EEM data matrix, M, can be conveniently represented as where x(i) and y(i) t are the observed excitation and emission spectra of the i th component and α i is a concentration dependent parameter. Such a data matrix is readily interpreted using linear algebraic procedures. Recently a new instrument has been described which rapidly acquires fluorescence detected circular dichroism (FDCD) data for chiral fluorophores as a function of multiple excitation and emission wavelengths. The FDCD matrix is similar in form to EEM data. However, since the FDCD matrix may have legitimate negative entries while the EEM is theoretically non-negative, different assumptions are required. This paper will describe the mathematical algorithms developed in this laboratory for the interpretation of the EEM in various forms. Particular emphasis will be placed on linear algebraic and two-dimensional Fourier Transform procedures.

Fluorescence-detected circular dichroism of ethidium in vivo and bound to deoxyribonucleic acid in vitro.

Fluorescence-detected circular dichroism (FDCD) spectra are reported for ethidium in Escherichia coli cells and bound to E. coli DNA in vitro. FDCD bands are observed at 325 and 385 nm. These bands change amplitude as the ethidium to DNA ratio changes. Spectra are similar for in vivo and in vitro measurements. However, the bands at 325 and 385 nm disappear when ethidium binds to macromolecules without intercalating between base pairs. The results demonstrate that FDCD spectra can be measured in cell suspensions and indicate that ethidium binds to nucleic acids in E. coli cells by intercalation.

One-dimensional aromatic crystals in solution. 4. Ground- and excited-state interactions of poly(L-1-pyrenylalanine) studied by chiroptical spectroscopy including circularly polarized fluorescence and fluorescence-detected circular dichroism

Synthese sous forme d'un copolymere sequence avec du poly DL-glutamate de gamma-benzyle comme unite solubilisante; etude des solutions dans le DMF et le phosphate de trimethyle. L'excimere du polymere a faible longueur d'onde est non polaire

Multidimensional luminescence measurements

Abstract : Luminescence spectroscopy has long been recognized as a tool for the quantitative and qualitative identification of a wide range of molecular systems. However, the resolving power of these techniques is often limited for similar compounds because absorption and emission peaks are typically broad banded and leads to overlapping spectra. To increase the resolving power of luminescence studies, recent studies have used multidimensional luminescence measurements (MLM) (use of two or more parameters of luminescence) to increase selectivity. Complex mixtures may be analyzed by rapidly acquiring fluorescence data as a function of multiple excitation and emission wavelengths. Advances in instrumentation and data reduction strategies allow the discrimination of mixtures in overlapping spectra by capitalizing on differences in fluorescence lifetime or fluorescence depolarization measurements. Fluorescence detected circular dichroism (FDCD) has been used to resolve optically active fluorescent compounds. Additionally, luminescence measurements may be combined with a range of measurements such as quenchometry and chromatography to yield very selective determinations.

Electronic interactions in one-dimensional chromophoric assemblies

Preparation of chromophoric polypeptides of the form I was described. These polymers were found to support regular helical arrangement of the chromophores along the polypeptide chain. The electronic excited states of these polymers were investigated by using novel chiroptical fluorescence spectroscopy, i.e., circularly polarized fluorescence (CPF) and fluorescence-detected circular dichroism (FDCD). The naphthyl polypeptides showed no or little excimer emission, indicating the stiffness of the regular helical chromophoric array. The pyrenyl polypeptide showed two types of excimers; one is formed in the disordered part of the helix, whereas the other is formed in the helical part without large conformational deformation. The aromatic polypeptides were considered as examples of one-dimensional chromophoric assemblies and their behaviors in the electronic excited states were discussed. A new electronic state which is coupled with lattice vibration, i.e., a soliton state, was first proposed for the one-dimensional system.

Use of circularly polarized light to study biological macromolecules

Abstract

Structural effects on the circular dichroism of ethidium ion-nucleic acid complexes.

Binding of the frameshift mutagen ethidium bromide to eight dinucleoside phosphates of different complementary base sequences, to trinucleoside diphosphates with mismatched bases capable of forming bulged structures (CpUpG and GpUpG + CpC), and to calf thymus DNA at different counterion concentrations was studied by optical methods, notably UV-visible spectroscopy, circular dichroism (CD), and fluorescence-detected circular dichroism (FDCD). The ethidium ion intercalated between the base pairs of the minihelix formed by the complementary dimers and displaced the mismatched bases to form bulged structures with the trimers. The stoichiometry of the complexes was 2:1 oligonucleotide:dye (or 1:1:1 for non-self-complementary species). Equilibrium constants for complex formation showed a general preference for dye binding to complementary sequences. Above 300 nm, where only the dye absorbs light, the induced CD spectra of the complexes had bands at 510, 375, 330, and 307 nm, with the magnitude of the 307-nm band, per bound dye, being the largest and sequence dependent. The CD spectra down to 220 nm of some complexes were obtained by FDCD measurements; between 220 and 300 nm, both the positions and the magnitudes of the bands were sequence dependent. At very low ionic strength, complexes of calf thymus DNA plus ethidium ion inmore » different salt concentrations showed that the 307-nm CD magnitude increased with decreasing counterion concentration. Implications of the results for theories of the induced CD spectrum of the ethidium ion are discussed.« less

ChemInform Abstract: FURTHER VERIFICATION OF FLUORESCENCE‐DETECTED CIRCULAR DICHROISM

Chemischer InformationsdienstVolume 12, Issue 12 Physical Organic Chemistry ChemInform Abstract: FURTHER VERIFICATION OF FLUORESCENCE-DETECTED CIRCULAR DICHROISM E. W. LOBENSTINE, E. W. LOBENSTINESearch for more papers by this authorD. H. TURNER, D. H. TURNERSearch for more papers by this author E. W. LOBENSTINE, E. W. LOBENSTINESearch for more papers by this authorD. H. TURNER, D. H. TURNERSearch for more papers by this author First published: March 24, 1981 https://doi.org/10.1002/chin.198112066AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue12March 24, 1981 RelatedInformation

Further verification of fluorescence-detected circular dichroism

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFurther verification of fluorescence-detected circular dichroismEric W. Lobenstine and Douglas H. TurnerCite this: J. Am. Chem. Soc. 1980, 102, 26, 7786–7787Publication Date (Print):December 1, 1980Publication History Published online1 May 2002Published inissue 1 December 1980https://doi.org/10.1021/ja00546a029RIGHTS & PERMISSIONSArticle Views117Altmetric-Citations15LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (278 KB) Get e-Alerts Get e-Alerts

Circular dichroism and fluorescence-detected circular dichroism of deoxyribonucleic acid and poly[d(A-C).cntdot.d(G-T)] in ethanolic solutions: a new method for estimating circular intensity differential scattering

A method is presented for determining the circular dichroism (CD) of systems whose CD spectra contain contributions from CD differential scattering. The technique is shown to detect light over 4 pi steradians, and thus, for the first time, a complete correction for scattering is possible. The method is applied to ethanol-condensed DNA and poly[d(A-C).d(G-T)]. From the results obtained, the former are proposed to have an A-type secondary structure. The condensed polynucleotide particles are shown to exhibit behavior similar to that of cholesteric liquid crystals. CD difference spectra, obtained from the scattering corrections and showing the contributions to different sections of the scattering envelope, are displayed. It is asserted that these scattering patterns contain information about the tertiary structure of the condensed DNA particles studied.

The optical activity of nucleic acids and their aggregates.

This review includes experimental and theoretical work on absorption and scattering of light by chiral macromolecules. All molecules absorb light, but only chiral (handed) molecules show a preferential absorption for right or left circularly polarized light. This phenomenon of circular dichroism (CD) has been very useful in characterizing any chiral aggre­ gate of chromophores-including proteins, nucleic acids, and their complexes. We discuss theoretical methods that relate the absorption and circular dichroism of a polymer or aggregate to the optical proper­ ties of its constituent parts. The experimental data reviewed is limited essentially to nucleic acids, for lack of space. Two new experimental methods that are particularly useful for mac­ romolecules or for systems that scatter a significant fraction of the incident light are fluorescence-detected circular dichroism and circular intensity differential scattered light. Fluorescence-detected circular di­ chroism (FDCD), as the name implies, used the intensity of the fluores­ cence emitted to monitor the intensity of the light absorbed (167). This method provides two main advantages: (a) The spectrum of a complex system containing many chromophores, but only a few fluorophores is greatly simplified, and (b) scattering artifacts, which plague circular dichroism studies using transmitted light measurements, are partly avoided by use of fluorescence detection. The theory (159, 160) and

Fluorescence‐detected circular dichroism of dinucleoside phosphates. A study of solution conformations and the two‐state model

AbstractThree fluorescent dinucleoside phosphates containing 1,N6‐ethenoadenosine (εA), εApεA, εApεC, and εApU were studied using fluorescence‐detected circular dichroism (FDCD), circular dichroism (CD), and absorption measurements. The FDCD data indicate that εApεC and εApU can be described as two‐state systems consisting of a fluorescent species and a stacked, nonfluorescent species. Thermodynamic stacking parameters are calculated for these molecules using the van't Hoff equation. εApεA is found to be a more complicated system with a fluorescent CD which is different in shape, but comparable in magnitude, to the conventional CD of the dimer. This molecule, unlike the other two dinucleoside phosphates, cannot be characterized as a two‐state system; it is described as consisting of at least three states at temperatures above 35°C. The CD data were subjected to a linear analysis in order to determine the minimum number of states present. In agreement with the FDCD data, εApεC and εApU are found to consist of a minimum of two states, while εApεA is indicated to have at least three. The more complicated behavior of the latter dimer is also indicated by the values of the unstacked CD obtained in the van't Hoff analysis.

ChemInform Abstract: PHOTOSELECTED FLUORESCENCE DETECTED CIRCULAR DICHROISM

Chemischer InformationsdienstVolume 10, Issue 31 Physical Organic Chemistry ChemInform Abstract: PHOTOSELECTED FLUORESCENCE DETECTED CIRCULAR DICHROISM E. W. LOBENSTINE, E. W. LOBENSTINESearch for more papers by this authorD. H. TURNER, D. H. TURNERSearch for more papers by this author E. W. LOBENSTINE, E. W. LOBENSTINESearch for more papers by this authorD. H. TURNER, D. H. TURNERSearch for more papers by this author First published: July 31, 1979 https://doi.org/10.1002/chin.197931062AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue31July 31, 1979 RelatedInformation

8] Fluorescence-detected circular dichroism

Publisher Summary This chapter focuses on the fluorescence-detected circular dichroism (FDCD). Circular dichroism (CD) is used extensively to the study of conformational changes in macromolecules. It measures the difference in absorption for left and fight circularly polarized light. FDCD detects the same difference by measuring the difference in fluorescence intensity excited by left and fight circularly polarized light. The fluorescence detection leads to several advantages over conventional CD. For one, it adds the specificity and sensitivity of fluorescence to the conformational discrimination of CD. In principle, another advantage is that FDCD can provide not only the average optical activity, but also the CD along one direction in the molecule. The excitation spectrum should follow the absorption spectrum of the Y base in the tRNA. By comparing this spectrum with the spectra calculated from various geometries, it is theoretically possible to draw conclusions concerning the conformation around the Y base. FDCD appears to be a powerful new technique for investigating local structure in macromolecules.

Fluorescence detected circular dichroism and circular polarization of luminescence in rigid media: Direction dependent optical activity obtained by photoselection

The fluorescence detected circular dichroism (FDCD) and circular polarization of luminescence (CPL) of rigid systems is related to molecular parameters. It is found that FDCD can yield the CD for light incident along the direction of the fluorescence transition moment. The average CD can also be measured as in a fluid medium. From CPL measurements one can evaluate the optical activity for light incident along the direction of the absorption transition moment. Thus, photoselection provides a method for measuring the direction dependent CD or optical activity of a molecule without actually orienting the molecule.

Effect of photoselection on fluorescence-detected circular dichroism

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of photoselection on fluorescence-detected circular dichroismB. Ehrenberg and I. Z. SteinbergCite this: J. Am. Chem. Soc. 1976, 98, 5, 1293–1295Publication Date (Print):March 1, 1976Publication History Published online1 May 2002Published inissue 1 March 1976https://doi.org/10.1021/ja00421a057RIGHTS & PERMISSIONSArticle Views117Altmetric-Citations30LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (439 KB) Get e-Alerts Get e-Alerts