scholarly journals Tapping into Synchrotron and Benchtop Circular Dichroism Spectroscopy for Expanding Studies of Complex Polysaccharides and their Interactions in Anoxic Archaeological Wood

Heritage ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 121-134
Author(s):  
Mary K. Phillips-Jones ◽  
Stephen E. Harding
Keyword(s):  
Circular Dichroism ◽  
Conformational Changes ◽  
Spectral Characteristics ◽  
Visible Region ◽  
Cd Spectroscopy ◽  
Future Research ◽  
Ultraviolet Region ◽  
Synchrotron Source ◽  
Archaeological Wood ◽  
Circular Dichroïsm

Circular dichroism (CD) (and synchrotron circular dichroism (SCD)) spectroscopy is a rapid, highly sensitive technique used to investigate structural conformational changes in biomolecules in response to interactions with ligands in solution and in film. It is a chiroptical method and at least one of the interacting molecules must possess optical activity (or chirality). In this review, we compare the capabilities of CD and SCD in the characterisation of celluloses and lignin polymers in archaeological wood. Cellulose produces a range of spectral characteristics dependent on environment and form; many of the reported transitions occur in the vacuum-ultraviolet region (< 180 nm) most conveniently delivered using a synchrotron source. The use of induced CD in which achiral dyes are bound to celluloses to give shifted spectra in the visible region is also discussed, together with its employment to identify the handedness of the chiral twists in nanocrystalline cellulose. Lignin is one target for the design of future consolidants that interact with archaeological wood to preserve it. It is reportedly achiral, but here we review several studies in which CD spectroscopy has successfully revealed lignin interactions with chiral enzymes, highlighting the potential usefulness of the technique in future research to identify new generation consolidants.

scholarly journals Questions of Mirror Symmetry at the Photoexcited and Ground States of Non-Rigid Luminophores Raised by Circularly Polarized Luminescence and Circular Dichroism Spectroscopy: Part 1. Oligofluorenes, Oligophenylenes, Binaphthyls and Fused Aromatics

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2606 ◽  
Author(s):  
Michiya Fujiki ◽  
Julian Koe ◽  
Takashi Mori ◽  
Yoshihiro Kimura
Keyword(s):  
Circular Dichroism ◽  
Mirror Symmetry ◽  
Neutral Current ◽  
Visible Region ◽  
Cd Spectroscopy ◽  
Mirror Image ◽  
Circularly Polarized ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence ◽  
Circular Dichroïsm

We report experimental tests of whether non-rigid, π-conjugated luminophores in the photoexcited (S1) and ground (S0) states dissolved in achiral liquids are mirror symmetrical by means of circularly polarized luminescence (CPL) and circular dichroism (CD) spectroscopy. Herein, we chose ten oligofluorenes, eleven linear/cyclic oligo-p-arylenes, three binaphthyls and five fused aromatics, substituted with alkyl, alkoxy, phenyl and phenylethynyl groups and also with no substituents. Without exception, all these non-rigid luminophores showed negative-sign CPL signals in the UV-visible region, suggesting temporal generation of energetically non-equivalent non-mirror image structures as far-from equilibrium open-flow systems at the S1 state. For comparison, unsubstituted naphthalene, anthracene, tetracene and pyrene, which are achiral, rigid, planar luminophores, did not obviously show CPL/CD signals. However, camphor, which is a rigid chiral luminophore, showed mirror-image CPL/CD signals. The dissymmetry ratio of CPL (glum) for the oligofluorenes increased discontinuously, ranging from ≈ −(0.2 to 2.0) × 10−3, when the viscosity of the liquids increased. When the fluorene ring number increased, the glum value extrapolated at [η] = 0 reached −0.8 × 10−3 at 420 nm, leading to (–)-CPL signals predicted in the vacuum state. Our comprehensive CPL and CD study should provide a possible answer to the molecular parity violation hypothesis arising due to the weak neutral current mediated by the Z0-boson.

Circular dichroism and synchrotron radiation circular dichroism spectroscopy: tools for drug discovery

2003 ◽  
Vol 31 (3) ◽  
pp. 631-633 ◽  
Author(s):  
B.A. Wallace ◽  
Robert W. Janes
Keyword(s):  
Circular Dichroism ◽  
Drug Discovery ◽  
Synchrotron Radiation ◽  
High Throughput ◽  
Conformational Changes ◽  
High Throughput Screening ◽  
Cd Spectroscopy ◽  
Drug Binding ◽  
Apoptosis Protein ◽  
Circular Dichroïsm

CD spectroscopy is an established and valuable technique for examining protein structure, dynamics and folding. Because of its ability to sensitively detect conformational changes, it has important potential for drug discovery, enabling screening for ligand and drug binding, and detection of potential candidates for new pharmaceuticals. The binding of the anti-tumour agent Taxol to the anti-apoptosis protein Bcl-2 [Rodi, Janes, Sanganee, Holton, Wallace and Makowski (1999) J. Mol. Biol. 285, 197–204] and the binding of the anti-epileptic drug lamotrigine to voltage-gated sodium channels [Cronin, O'Reilly, Duclohier and Wallace (2003) J. Biol. Chem. 278, 10675–10682] are used as examples to show changes detectable by CD involving secondary structure, and are contrasted with the binding of the agonist carbamylcholine to acetylcholine receptors [Mielke and Wallace (1988) J. Biol. Chem. 263, 8177–8182], an example where binding does not involve a secondary structural change. Synchrotron radiation CD spectroscopy offers significant enhancements with respect to conventional CD spectroscopy, which will enable its usage for high-throughput screening and as a tool in ‘chemical genomics’ or ‘reverse chemical genetics’ strategies for ligand identification. The lower wavelength data available enable more detailed, sensitive and accurate detection, the higher light intensity permits much smaller amounts of both proteins and drug candidates to be used in the screening, and future technological developments in sample handling and detection should enable automated high-throughput screening to be performed.

scholarly journals Calibration and standardisation of synchrotron radiation and conventional circular dichroism spectrometers. Part 2: Factors affecting magnitude and wavelength

2005 ◽  
Vol 19 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Andrew J. Miles ◽  
Frank Wien ◽  
Jonathan G. Lees ◽  
B.A. Wallace
Keyword(s):  
Circular Dichroism ◽  
Synchrotron Radiation ◽  
Secondary Structure ◽  
Optical Rotation ◽  
Good Practice ◽  
Protein Secondary Structure ◽  
Cd Spectroscopy ◽  
Synchrotron Source ◽  
Calibration Methods ◽  
Circular Dichroïsm

Circular dichroism (CD) spectroscopy is an important tool in structural biology, especially for protein secondary structure analyses. Synchrotron radiation circular dichroism (SRCD) spectroscopy is a modified version of the technique that uses the intense light from a synchrotron source to enable the collection of data to much lower wavelengths than possible on conventional circular dichroism (cCD) instruments. There is a need for standardization of calibration methods amongst and between cCD and SRCD instruments to ensure consistency and the ability to use common reference databases for empirical secondary structural analyses. In a previous study (Spectroscopy17(2003), 653–661), we compared optical rotation measurements on several cCD and SRCD instruments, whilst holding constant other experimental factors. In this study, other experimental parameters which contribute to the spectral magnitude, such as cell pathlength and protein concentration determinations, are examined. In addition, the extent of wavelength calibration variations between instruments and their effects on secondary structure calculations have been examined. Hence, this paper provides additional practical guidance for “good practice” in the measurement of CD data.

scholarly journals Characterisation of sensor kinase by CD spectroscopy: golden rules and tips

2018 ◽  
Vol 46 (6) ◽  
pp. 1627-1642 ◽  
Author(s):  
Giuliano Siligardi ◽  
Charlotte S. Hughes ◽  
Rohanah Hussain
Keyword(s):  
Circular Dichroism ◽  
Membrane Proteins ◽  
Conformational Changes ◽  
High Throughput Screening ◽  
Local Environment ◽  
Cd Spectroscopy ◽  
Photon Flux ◽  
Minimal Amount ◽  
Sensor Kinase ◽  
Circular Dichroïsm

This is a review that describes the golden rules and tips on how to characterise the molecular interactions of membrane sensor kinase proteins with ligands using mainly circular dichroism (CD) spectroscopy. CD spectroscopy is essential for this task as any conformational change observed in the far-UV (secondary structures (α-helix, β-strands, poly-proline of type II, β-turns, irregular and folding) and near-UV regions [local environment of the aromatic side-chains of amino acid residues (Phe, Tyr and Trp) and ligands (drugs) and prosthetic groups (porphyrins, cofactors and coenzymes (FMN, FAD, NAD))] upon ligand addition to the protein can be used to determine qualitatively and quantitatively ligand-binding interactions. Advantages of using CD versus other techniques will be discussed. The difference CD spectra of the protein–ligand mixtures calculated subtracting the spectra of the ligand at various molar ratios can be used to determine the type of conformational changes induced by the ligand in terms of the estimated content of the various elements of protein secondary structure. The highly collimated microbeam and high photon flux of Diamond Light Source B23 beamline for synchrotron radiation circular dichroism (SRCD) enable the use of minimal amount of membrane proteins (7.5 µg for a 0.5 mg/ml solution) for high-throughput screening. Several examples of CD titrations of membrane proteins with a variety of ligands are described herein including the protocol tips that would guide the choice of the appropriate parameters to conduct these titrations by CD/SRCD in the best possible way.

scholarly journals Questions of Mirror Symmetry at the Photoexcited and Ground States of Non-Rigid Luminophores Raised by Circularly Polarized Luminescence and Circular Dichroism Spectroscopy. Part 2: Perylenes, BODIPYs, Molecular Scintillators, Coumarins, Rhodamine B, and DCM

Symmetry ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 363
Author(s):  
Michiya Fujiki ◽  
Julian R. Koe ◽  
Seiko Amazumi
Keyword(s):  
Circular Dichroism ◽  
Rhodamine B ◽  
Mirror Symmetry ◽  
Visible Region ◽  
Cd Spectroscopy ◽  
Mirror Image ◽  
Circularly Polarized ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence ◽  
Circular Dichroïsm

We investigated whether semi-rigid and non-rigid π-conjugated fluorophores in the photoexcited (S1) and ground (S0) states exhibited mirror symmetry by circularly polarized luminescence (CPL) and circular dichroism (CD) spectroscopy using a range of compounds dissolved in achiral liquids. The fluorophores tested were six perylenes, six scintillators, 11 coumarins, two pyrromethene difluoroborates (BODIPYs), rhodamine B (RhB), and 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM). All the fluorophores showed negative-sign CPL signals in the ultraviolet (UV)–visible region, suggesting energetically non-equivalent and non-mirror image structures in the S1 state. The dissymmetry ratio of the CPL (glum) increased discontinuously from approximately −0.2 × 10−3 to −2.0 × 10−3, as the viscosity of the liquids increased. Among these liquids, C2-symmetrical stilbene 420 showed glum ≈ −0.5 × 10−3 at 408 nm in H2O and D2O, while, in a viscous alkanediol, the signal was amplified to glum ≈ −2.0 × 10−3. Moreover, BODIPYs, RhB, and DCM in the S0 states revealed weak (−)-sign CD signals with dissymmetry ratios (gabs) ≈ −1.4 × 10−5 at λmax/λext. The origin of the (−)-sign CPL and the (−)-sign CD signals may arise from an electroweak charge at the polyatomic level. Our CPL and CD spectral analysis could be a possible answer to the molecular parity violation hypothesis based on a weak neutral current of Z0 boson origin that could connect to the origin of biomolecular handedness.

scholarly journals Synthesis of a sucrose dimer with enone tether; a study on its functionalization

2014 ◽  
Vol 10 ◽  
pp. 1246-1254 ◽  
Author(s):  
Zbigniew Pakulski ◽  
Norbert Gajda ◽  
Magdalena Jawiczuk ◽  
Jadwiga Frelek ◽  
Piotr Cmoch ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Double Bond ◽  
Carbonyl Group ◽  
Osmium Tetroxide ◽  
Cd Spectroscopy ◽  
Allylic Alcohol ◽  
Circular Dichroïsm

The reaction of appropriately functionalized sucrose phosphonate with sucrose aldehyde afforded a dimer composed of two sucrose units connected via their C6-positions (‘the glucose ends’). The carbonyl group in this product (enone) was stereoselectively reduced with zinc borohydride and the double bond (after protection of the allylic alcohol formed after reduction) was oxidized with osmium tetroxide to a diol. Absolute configurations of the allylic alcohol as well as the diol were determined by circular dichroism (CD) spectroscopy using the in situ dimolybdenum methodology.

scholarly journals Conformational changes in the H3 . H4 histone complex. Serological and circular dichroism studies.

1980 ◽  
Vol 255 (15) ◽  
pp. 7059-7062
Author(s):  
L. Feldman ◽  
N.V. Beaudette ◽  
B.D. Stollar ◽  
G.D. Fasman
Keyword(s):  
Circular Dichroism ◽  
Conformational Changes ◽  
Circular Dichroïsm

scholarly journals Detection of Protein-Protein Interactions in the Alkanesulfonate Monooxygenase System from Escherichia coli

2006 ◽  
Vol 188 (23) ◽  
pp. 8153-8159 ◽  
Author(s):  
Kholis Abdurachim ◽  
Holly R. Ellis
Keyword(s):  
Circular Dichroism ◽  
Protein Interactions ◽  
Visible Region ◽  
Circular Dichroism Spectroscopy ◽  
Flavin Mononucleotide ◽  
Stable Complex ◽  
Monooxygenase System ◽  
Protein Protein Interactions ◽  
Alkanesulfonate Monooxygenase ◽  
Circular Dichroïsm

ABSTRACT The two-component alkanesulfonate monooxygenase system utilizes reduced flavin as a substrate to catalyze a unique desulfonation reaction during times of sulfur starvation. The importance of protein-protein interactions in the mechanism of flavin transfer was analyzed in these studies. The results from affinity chromatography and cross-linking experiments support the formation of a stable complex between the flavin mononucleotide (FMN) reductase (SsuE) and monooxygenase (SsuD). Interactions between the two proteins do not lead to overall conformational changes in protein structure, as indicated by the results from circular dichroism spectroscopy in the far-UV region. However, subtle changes in the flavin environment of FMN-bound SsuE that occur in the presence of SsuD were identified by circular dichroism spectroscopy in the visible region. These data are supported by the results from fluorescent spectroscopy experiments, where a dissociation constant of 0.0022 ± 0.0010 μM was obtained for the binding of SsuE to SsuD. Based on these studies, the stoichiometry for protein-protein interactions is proposed to involve a 1:1 monomeric association of SsuE with SsuD.

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