Changes in structural parameters with conformational changes and the determination of conformational stabilities by molecular spectroscopic techniques

1988 ◽  
Vol 173 ◽  
pp. 1-16 ◽  
Author(s):  
J.R. Durig ◽  
P. Groner ◽  
J.F. Sullivan
Keyword(s):  
Conformational Changes ◽  
Structural Parameters ◽  
Spectroscopic Techniques

Influence of Ascorbic Acid on the Structure and Function of Alpha-2- macroglobulin: Investigations using Spectroscopic and Thermodynamic Techniques

2020 ◽  
Vol 27 (3) ◽  
pp. 201-209
Author(s):  
Syed Saqib Ali ◽  
Mohammad Khalid Zia ◽  
Tooba Siddiqui ◽  
Haseeb Ahsan ◽  
Fahim Halim Khan
Keyword(s):  
Ascorbic Acid ◽  
Conformational Changes ◽  
Structural Changes ◽  
The Body ◽  
Titration Calorimetry ◽  
Spectroscopic Techniques ◽  
Human Beings ◽  
Plasma Ascorbic Acid ◽  
Dietary Antioxidant ◽  
And Function

Background: Ascorbic acid is a classic dietary antioxidant which plays an important role in the body of human beings. It is commonly found in various foods as well as taken as dietary supplement. Objective: The plasma ascorbic acid concentration may range from low, as in chronic or acute oxidative stress to high if delivered intravenously during cancer treatment. Sheep alpha-2- macroglobulin (α2M), a human α2M homologue is a large tetrameric glycoprotein of 630 kDa with antiproteinase activity, found in sheep’s blood. Methods: In the present study, the interaction of ascorbic acid with alpha-2-macroglobulin was explored in the presence of visible light by utilizing various spectroscopic techniques and isothermal titration calorimetry (ITC). Results: UV-vis and fluorescence spectroscopy suggests the formation of a complex between ascorbic acid and α2M apparent by increased absorbance and decreased fluorescence. Secondary structural changes in the α2M were investigated by CD and FT-IR spectroscopy. Our findings suggest the induction of subtle conformational changes in α2M induced by ascorbic acid. Thermodynamics signatures of ascorbic acid and α2M interaction indicate that the binding is an enthalpy-driven process. Conclusion: It is possible that ascorbic acid binds and compromises antiproteinase activity of α2M by inducing changes in the secondary structure of the protein.

Hydrodynamic determination of molecular weight, dimensions, and structural parameters of Pf3 virus

Biochemistry ◽  
1982 ◽  
Vol 21 (14) ◽  
pp. 3352-3358 ◽  
Author(s):  
Jay Newman ◽  
Loren A. Day ◽  
Gregory W. Dalack ◽  
Don Eden
Keyword(s):  
Molecular Weight ◽  
Structural Parameters

Comparative chemotype determination of Lamiaceae plants by means of GC–MS, FT-IR, and dispersive-Raman spectroscopic techniques and GC-FID quantification

2014 ◽  
Vol 62 ◽  
pp. 22-33 ◽  
Author(s):  
Raquel Rodríguez-Solana ◽  
Dimitra J. Daferera ◽  
Christina Mitsi ◽  
Panayiotis Trigas ◽  
Moschos Polissiou ◽  
...  
Keyword(s):  
Spectroscopic Techniques ◽  
Raman Spectroscopic ◽  
Ft Ir

Structure Determination of 3,5-Biscyclohexylidene-1,2,4-trithiolane / Structure Determination of 3,5-Biscyclohexylidene-1,2,4-trithiolane

1980 ◽  
Vol 35 (8) ◽  
pp. 1015-1018 ◽  
Author(s):  
Werner Winter ◽  
Hanspeter Bühl ◽  
Herbert Meier
Keyword(s):  
General Formula ◽  
Structure Determination ◽  
Title Compound ◽  
Direct Methods ◽  
Spectroscopic Techniques ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Final Structure

Abstract Fragmentation of 1,2,3-thiadiazoles (1) leads to the compounds 5 - 8 with an increasing proportion of sulphur. Numerous structural possibilities exist for the products 7 with the general formula (R2C2)2S3. The number of proposals can be reduced by spectroscopic techniques, but the final structure determination is accomplished by an X-ray analysis of the title compound 7a. 7a crystallizes in the space group P21/c (Z = 4) with cell parameters of a = 9.714(1), b = 16.188(8), c = 9.149(2) Å and β = 98.93(1)°. The structure is solved by direct methods and refined to R = 0.053 with 1955 diffractometer data (I ≥ 2σ(I)). The trithiolane ring has a puckered conformation and the whole molecule shows nearly perfect C2-symmetry, which is not required crystallographically.

scholarly journals Interpretation of the X-Ray Spectra of Solar Active Regions

1975 ◽  
Vol 68 ◽  
pp. 73-100 ◽  
Author(s):  
Arthur B. C. Walker
Keyword(s):  
Transition Region ◽  
Rate Constant ◽  
Active Regions ◽  
Temperature Structure ◽  
Spectroscopic Techniques ◽  
Density Structure ◽  
Coronal Temperature ◽  
X Ray ◽  
Euv Spectrum

This paper presents a review of recent analytical studies of the coronal X-ray spectrum below 25 Å. The techniques used to compute the theoretical coronal spectrum, and the currently available atomic rate constant data are reviewed first. Spectroscopic techniques which have been proposed for the determination of coronal temperature and density structure, and the results derived from their application to coronal spectra are also reviewed.A number of coronal models based on X-ray observations have been developed recently, and the coronal temperature structure and composition predicted by these models is discussed, and compared with models of the corona and transition region derived from studies of the solar EUV spectrum.

scholarly journals ASAXS study of CaF2nanoparticles embedded in a silicate glass matrix

2014 ◽  
Vol 47 (1) ◽  
pp. 60-66 ◽  
Author(s):  
Armin Hoell ◽  
Zoltan Varga ◽  
Vikram Singh Raghuwanshi ◽  
Michael Krumrey ◽  
Christian Bocker ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Spatial Distribution ◽  
Glass Matrix ◽  
Structural Parameters ◽  
Pixel Detector ◽  
Oxyfluoride Glass ◽  
X Ray ◽  
X Ray Scattering ◽  
Silicate Glass Matrix

The formation and growth of nanosized CaF2crystallites by heat treatment of an oxyfluoride glass of composition 7.65Na2O–7.69K2O–10.58CaO–12.5CaF2–5.77Al2O3–55.8SiO2(wt%) was investigated using anomalous small-angle X-ray scattering (ASAXS). A recently developed vacuum version of the hybrid pixel detector Pilatus 1M was used for the ASAXS measurements below the CaK-edge of 4038 eV down to 3800 eV. ASAXS investigation allows the determination of structural parameters such as size and size distribution of nanoparticles and characterizes the spatial distribution of the resonant element, Ca. The method reveals quantitatively that the growing CaF2crystallites are surrounded by a shell of lower electron density. This depletion shell of growing thickness hinders and finally limits the growth of CaF2crystallites. Moreover, in samples that were annealed for 10 h and more, additional very small heterogeneities (1.6 nm diameter) were found.

X-ray topographic determination of the granular structure in a graphite mosaic crystal: a three-dimensional reconstruction

2000 ◽  
Vol 33 (4) ◽  
pp. 1023-1030 ◽  
Author(s):  
M. Ohler ◽  
M. Sanchez del Rio ◽  
A. Tuffanelli ◽  
M. Gambaccini ◽  
A. Taibi ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Pyrolytic Graphite ◽  
Three Dimensional ◽  
X Ray ◽  
Dimensional Reconstruction ◽  
Mosaic Crystals ◽  
Spatial Locations ◽  
Crystalline Domains

Section topographs recorded at different spatial locations and at different rocking angles of a highly oriented pyrolytic graphite (HOPG) crystal allow three-dimensional maps of the local angular-dependent scattering power to be obtained. This is performed with a direct reconstruction from the intensity distribution on such topographs. The maps allow the extraction of information on local structural parameters such as size, form and internal mosaic spread of crystalline domains. This data analysis leads to a new method for the characterization of mosaic crystals. Perspectives and limits of applicability of this method are discussed.

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