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Marie-Martine Dujardin

Bio: Marie-Martine Dujardin is an academic researcher. The author has contributed to research in topics: Capsid & Medicine. The author has an hindex of 1, co-authored 1 publications receiving 74 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the optical constants of thin Ag films are determined from measurements of both their transmittance and reflectance, in terms of intra and interband transitions, in relation with the film crystallographic structure.
Abstract: The optical constants of thin Ag films are determined from measurements of both their transmittance and reflectance. The complex dielectric constant is discussed in terms of intra and interband transitions, in relation with the film crystallographic structure. The optical mass of the conduction electrons is found to be very low, 0·87; their optical relaxation time to depend strongly on the film structure and to be smaller than their electrical relaxation time. The absorption due to interband transitions is considered. A supplementary absorption band related to film imperfections is observed in some cases. Plasma oscillations are also studied in relation with the film quality.

75 citations

Journal ArticleDOI
TL;DR: It is shown that the recently developed proton‐detected fast magic‐angle‐spinning solid‐state NMR at >100 kHz MAS allows one to detect the C‐terminal domain of the hepatitis B virus capsid protein and unveil its structural and dynamic behavior.
Abstract: Abstract Experimentally determined protein structures often feature missing domains. One example is the C‐terminal domain (CTD) of the hepatitis B virus capsid protein, a functionally central part of this assembly, crucial in regulating nucleic‐acid interactions, cellular trafficking, nuclear import, particle assembly and maturation. However, its structure remained elusive to all current techniques, including NMR. Here we show that the recently developed proton‐detected fast magic‐angle‐spinning solid‐state NMR at >100 kHz MAS allows one to detect this domain and unveil its structural and dynamic behavior. We describe the experimental framework used and compare the domain's behavior in different capsid states. The developed approaches extend solid‐state NMR observations to residues characterized by large‐amplitude motion on the microsecond timescale, and shall allow one to shed light on other flexible protein domains still lacking their structural and dynamic characterization.

4 citations

Posted ContentDOI
05 Jan 2022
TL;DR: It is shown that the recently developed proton-detected fast magic-angle-spinning solid-state NMR at >100 kHz MAS is a game changer that allows to detect the C terminal domain of the hepatitis B virus capsid protein and unveil its structural and dynamic behavior.
Abstract: Experimentally determined protein structures often feature missing domains. One example is the C terminal domain (CTD) of the hepatitis B virus capsid protein, a functionally central part of this assembly, crucial in regulated nucleic-acid interactions, cellular trafficking, nuclear import, particle assembly and maturation. However, its structure remained elusive to all current techniques, including NMR. Here we show that the recently developed proton-detected fast magic-angle-spinning solid-state NMR at >100 kHz MAS is a game changer that allows to detect this domain and unveil its structural and dynamic behavior. We describe the experimental framework used and compare the domain’s behavior in different capsid states. The developed approaches extend solid-state NMR observations to residues characterized by large-amplitude motion on the microsecond timescale, and shall allow to shed light on other flexible protein domains still lacking their structural and dynamic characterization.

2 citations

Journal ArticleDOI
TL;DR: In this paper , solid-state NMR was used to reveal that the asymmetric unit comprises a single Cp molecule rather than the four quasi-equivalent conformers typical for the icosahedral T = 4 symmetry of the normal HBV capsids.
Abstract: Abstract Hepatitis B virus (HBV) capsid assembly modulators (CAMs) represent a recent class of anti-HBV antivirals. CAMs disturb proper nucleocapsid assembly, by inducing formation of either aberrant assemblies (CAM-A) or of apparently normal but genome-less empty capsids (CAM-E). Classical structural approaches have revealed the CAM binding sites on the capsid protein (Cp), but conformational information on the CAM-induced off-path aberrant assemblies is lacking. Here we show that solid-state NMR can provide such information, including for wild-type full-length Cp183, and we find that in these assemblies, the asymmetric unit comprises a single Cp molecule rather than the four quasi-equivalent conformers typical for the icosahedral T = 4 symmetry of the normal HBV capsids. Furthermore, while in contrast to truncated Cp149, full-length Cp183 assemblies appear, on the mesoscopic level, unaffected by CAM-A, NMR reveals that on the molecular level, Cp183 assemblies are equally aberrant. Finally, we use a eukaryotic cell-free system to reveal how CAMs modulate capsid-RNA interactions and capsid phosphorylation. Our results establish a structural view on assembly modulation of the HBV capsid, and they provide a rationale for recently observed differences between in-cell versus in vitro capsid assembly modulation.

1 citations

Journal ArticleDOI
TL;DR: This work performed pharmacomodulation of pocket binders through systematic modifications of the three distinct chemical moieties composing the Triton X-100 molecule and found that the flat aromatic moiety is essential for binding, while the number of atoms of the aliphatic chain modulates binding affinity.
Abstract: Hepatitis B virus (HBV) is a small enveloped retrotranscribing DNA virus and an important human pathogen. Its capsid-forming core protein (Cp) features a hydrophobic pocket proposed to be central notably in capsid envelopment. Indeed, mutations in and around this pocket can profoundly modulate, and even abolish, secretion of enveloped virions. We have recently shown that Triton X-100, a detergent used during Cp purification, binds to the hydrophobic pocket with micromolar affinity. We here performed pharmacomodulation of pocket binders through systematic modifications of the three distinct chemical moieties composing the Triton X-100 molecule. Using NMR and ITC, we found that the flat aromatic moiety is essential for binding, while the number of atoms of the aliphatic chain modulates binding affinity. The hydrophilic tail, in contrast, is highly tolerant to changes in both length and type. Our data provide essential information for designing a new class of HBV antivirals targeting capsid–envelope interactions.

1 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the pump-probe signals near the plasmon resonance of the nanoparticles reveal the importance of electron-electron scattering during several hundreds of femtoseconds.
Abstract: We studied the dynamics of electrons in copper and silver nanoparticles embedded in a transparent matrix, using the technique of pump–probe femtosecond spectroscopy. Comparative measurements are made in thin films of the same metals. In the case of the nanoparticles, the electron dynamics is strongly influenced by the surface at the boundary of the metal and the surrounding dielectric matrix. A detailed study of the pump–probe signals near the plasmon resonance of the nanoparticles reveals the importance of electron–electron scattering during several hundreds of femtoseconds. The influence of these scattering processes on the real and imaginary parts of the metal dielectric function is compared in the nanoparticles and thin films. In addition, the non-thermal component of the electrons and the heat transfer to the surrounding dielectric are measured. The results are analyzed with a model of effective medium, where the metal dielectric function is described in the random phase approximation, including the surface effects in a phenomenological way.

310 citations

Journal ArticleDOI
TL;DR: The ideal spectral properties are treated, an illustrative experimental example of how well this goal can be realized is given, and a corresponding theoretical curve is shown indicating to what extent the measured results can be theoretically understood.
Abstract: Matter continuously exchanges energy with its surroundings. This exchange can be dominated by radiation, conduction, or convection. In this brief review we discuss how proper design of radiative surface properties can be used for heating and cooling purposes. The desired properties can be understood once it is realized that solar and terrestrial radiation take place in different wavelength ranges and that only part of the solar spectrum is useful for vision and for photosynthesis in plants. These facts allow the possibility of tailoring the spectral absorptance, emittance, reflectance, and transmittance of a surface to meet different demands in different wavelength intervals, i.e., to take advantage of spectral selectivity. One example is the selective surface for efficient photothermal conversion of solar energy, which has high absorptance over the solar spectrum but low emittance for the longer wavelengths relevant to thermal reradiation. Below we discuss the pertinent spectral radiative properties of our ambience. These data are then used as background to the subsequent sections treating four examples of spectrally selective surfaces. The first example is the previously mentioned selective surface for converting solar radiation to useful heat. The second example considers surfaces capable of reaching low temperatures by benefiting from the spectral emittance of the clear night sky. The third example concerns two related types of transparent heat mirror. The fourth example, finally, treats radiative cooling of green leaves; this part is included since it gives a nice example of how nature solves a difficult problem in an elegant and efficient way. This example hence provides an interesting background to the other cruder types of artificial selective surfaces. Throughout our discussion we treat the ideal spectral properties, give an illustrative experimental example of how well this goal can be realized, and—where this is possible—show a corresponding theoretical curve indicating to what extent the measured results can be theoretically understood.

264 citations

Journal ArticleDOI
TL;DR: In this article, the surface plasmons in silver films with narrow straight grooves were visualized in unprecedented detail by means of near-field optical techniques, and their values were determined semiquantitatively.
Abstract: Excitation and propagation of surface plasmons in silver films structured with narrow straight grooves were visualized in unprecedented detail by means of near-field optical techniques. Reflectivity, transmissivity, and scattering loss of the grooves are demonstrated. Their values are determined semiquantitatively. The surface plasmon attenuation are found to be dominated by material and surface/interface imperfections.

148 citations

Journal ArticleDOI
TL;DR: In this paper, the dispersion of surface plasmons at an air-metal interface has been studied experimentally using the method of attenuated total reflection, and it was shown that surface plasmon interactions must be characterized by a complete response-function surface rather than by a single dispersion curve.
Abstract: The dispersion of surface plasmons at an air-metal interface has been studied experimentally using the method of attenuated total reflection. In the vicinity of the surface plasmon energy the dispersion curve was found to bend back toward the light line instead of increasing asymptotically to the surface plasmon energy at infinite momentum. We conclude that surface plasmon interactions must be characterized by a complete response-function surface rather than by a single dispersion curve.

125 citations

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate how to obtain the ultimate lateral resolution in surface plasmon microscopy (SPM) (diffraction limited by the objective) by determining the optimal depth values for wavelengths ranging from 531 to 676 nm.
Abstract: In this article we demonstrate how to obtain the ultimate lateral resolution in surface plasmon microscopy (SPM) (diffraction limited by the objective). Surface plasmon decay lengths are determined theoretically and experimentally, for wavelengths ranging from 531 to 676 nm, and are in good agreement. Using these values we can determine for each particular situation which wavelength should be used to obtain an optimal lateral resolution, i.e., where the plasmon decay length does not limit the resolution anymore. However, there is a trade‐off between thickness resolution and lateral resolution in SPM. Because of the non‐optimal thickness resolution, we use several techniques to enhance the image acquisition and processing. Without these techniques the use of short wavelengths results in images where the contrast has vanished almost completely. In an example given, a 2.5 nm SiO2 layer on a gold layer is imaged with a lateral resolution of 2 μm, and local reflectance curves are measured to determine the laye...

124 citations