Search results for "Spectrum Analysi"
showing 10 items of 287 documents
Dielectric Relaxations in Confined Hydrated Myoglobin
2009
In this work we report the results of a broadband dielectric spectroscopy study on the dynamics of a globular protein, myoglobin, in confined geometry, i.e. encapsulated in a porous silica matrix, at low hydration levels, where about only one or two water layers surround the proteins. In order to highlight the specific effect of confinement in the silica host, we compared this system with hydrated myoglobin powders at the same hydration levels. The comparison between the data relative to the two different systems indicates that geometrical confinement within the silica matrix plays a crucial role in protein-water dielectric relaxations, the effect of sol-gel encapsulation being essentially …
Membrane Structure of Aquaporin Observed with Combined Experimental and Theoretical Sum Frequency Generation Spectroscopy
2021
High-resolution structural information on membrane proteins is essential for understanding cell biology and for the structure-based design of new medical drugs and drug delivery strategies. X-ray diffraction (XRD) can provide angstrom-level information about the structure of membrane proteins, yet for XRD experiments, proteins are removed from their native membrane environment, chemically stabilized, and crystallized, all of which can compromise the conformation. Here, we describe how a combination of surface-sensitive vibrational spectroscopy and molecular dynamics simulations can account for the native membrane environment. We observe the structure of a glycerol facilitator channel (GlpF)…
Local dynamic properties of the heme pocket in native and solvent-induced molten-globule-like states of cytochrome c
2002
We report the Soret absorption band, down to cryogenic temperature, of native and molten-globule-like state of horse heart cytochrome c. The band profile is analyzed in terms of vibronic coupling of the heme normal modes to the electronic transition in the framework of the Franck-Condon approximation. From the temperature dependence of the Gaussian broadening and of the peak position, we obtain information on the 'bath' of low frequency harmonic motions of the heme group within the heme pocket. The reported data indicate that, compared to the native state, the less rigid tertiary structure of the molten globule is reflected in a higher flexibility of the heme pocket and in greater conformat…
Isolation and Characterization of Epidermal DNA and RNA from Guinea Pig Skin
1971
DNA and RNA were isolated from mammalian epidermis in a relatively small scale procedure. The high purity and native state of the DNA isolated is reflected by its molar absorptivity E (P), its thermal hyperchromicity and its hyperchromicity upon DNase treatment and by its sedimentation profile as well as by its profile in a cesium chloride density gradient. The very low content of protein and RNA, as well as the data of DNA determination, indicate that this method permits the isolation of a highly purified product. This is further substantiated by the determination of UV absorption spectra and by analysis of the base composition.The mammalian skin DNA showed the following properties: Mol. w…
Study of the Mode and Efficiency of DNA Binding in the Damage Induced by Photoactivated Water Soluble Porphyrins
2013
We have investigated the DNA binding interactions and in vitro photoactivated DNA damage induced by a neutral water soluble porphyrin derivative 5,10,15,20-tetrakis(2,4,6-trihydroxyphenyl)porphyrin (TTHPP) and its zinc derivative 5,10,15,20-tetrakis(2,4,6-trihydroxyphenyl)porphyrinato zinc(II) (Zn-TTHPP) upon visible light irradiation through various spectroscopic techniques and employing repair endonucleases. These porphyrin derivatives exhibited high affinity toward DNA through groove binding interactions as evidenced through the UV-vis absorption, emission, circular dichroism spectral and viscosity changes. Interestingly, the free base porphyrin derivative, TTHPP generated efficient sing…
A new multi analytical approach for the identification of synthetic and natural dyes mixtures. The case of orcein-mauveine mixture in a historical dr…
2017
In this paper, the application of a multi-analytical approach for the characterisation of synthetic and natural dyes in a historical textile is presented. The work is focused on a historical dress of a Sicilian noblewoman, dating from about 1865–1870. Firstly, SERS on fibre was performed, in order to individuate the classes of dyes employed. The SERS spectra suggested the presence of two main dyes: mauveine and orcein. In order to confirm these preliminary results, two different extraction protocols were applied. The extracts obtained were analysed by ESI-MS, MALDI-ToF and UHPCL-MS analyses, confirming the SERS results. In particular, the application of the ammonia mild extraction technique…
Raman Spectroscopic Signatures of Echovirus 1 Uncoating
2014
ABSTRACT In recent decades, Raman spectroscopy has entered the biological and medical fields. It enables nondestructive analysis of structural details at the molecular level and has been used to study viruses and their constituents. Here, we used Raman spectroscopy to study echovirus 1 (EV1), a small, nonenveloped human pathogen, in two different uncoating states induced by heat treatments. Raman signals of capsid proteins and RNA genome were observed from the intact virus, the uncoating intermediate, and disrupted virions. Transmission electron microscopy data revealed general structural changes between the studied particles. Compared to spectral characteristics of proteins in the intact v…
Tumour tissue monitoring during photodynamic and hyperthermic treatment using bioimpedance spectroscopy.
2003
Electrical bioimpedance spectroscopy is a fast and relatively easily applicable method for tissue characterization. In the frequency range up to 10 MHz, current conduction through tissue is mainly determined by tissue structure, i.e. the extra- and intra-cellular compartments and the insulating cell membranes. Therefore, changes in the extra- and intra-cellular fluid volumes are reflected in the impedance spectra. Investigations of tumours (DS sarcoma, implanted on the hind foot dorsum of rats) during treatment with localized hyperthermia (HT), photodynamic therapy (PDT) and the combination of these two components were carried out using impedance spectroscopy in the frequency range of 37 Hz…
Core–Shell Nanorod Columnar Array Combined with Gold Nanoplate–Nanosphere Assemblies Enable Powerful In Situ SERS Detection of Bacteria
2016
Development of a label-free ultrasensitive nanosensor for detection of bacteria is presented. Sensitive assay for Gram-positive bacteria was achieved via electrostatic attraction-guided plasmonic bifacial superstructure/bacteria/columnar array assembled in one step. Dynamic optical hotspots were formed in the hybridized nanoassembly under wet-dry critical state amplifying efficiently the weak vibrational modes of three representative food-borne Gram-positive bacteria, that is, Staphylococcus xylosus, Listeria monocytogenes, and Enterococcus faecium. These three bacteria with highly analogous Raman spectra can be effectively differentiated through droplet wet-dry critical SERS approach combi…
Gold Nanoparticle Growth Monitored in situ Using a Novel Fast Optical Single-Particle Spectroscopy Method
2007
Size- and shape-dependent optical properties of gold nanorods allow monitoring their growth using a novel fast single-particle spectroscopy (fastSPS) method. FastSPS uses a spatially addressable electronic shutter based on a liquid crystal device to investigate particles randomly deposited on a substrate, orders of magnitude faster than other techniques. We use fastSPS to observe nanoparticle growth in situ on a single-particle level and extract quantitative data on nanoparticle growth.