Search results for " Scanning"

Jararhagin-derived RKKH Peptides Induce Structural Changes in α1I Domain of Human Integrin α1β1

2003

Integrin alpha(1)beta(1) is one of four collagen-binding integrins in humans. Collagens bind to the alphaI domain and in the case of alpha(2)I collagen binding is competitively inhibited by peptides containing the RKKH sequence and derived from the metalloproteinase jararhagin of snake venom from Bothrops jararaca. In alpha(2)I, these peptides bind near the metal ion-dependent adhesion site (MIDAS), where a collagen (I)-like peptide is known to bind; magnesium is required for binding. Published structures of the ligand-bound "open" conformation of alpha(2)I differs significantly from the "closed" conformation seen in the structure of apo-alpha(2)I near MIDAS. Here we show that two peptides,…

Irreversible gelation of thermally unfolded proteins:structural and mechanical properties of lysozyme aggregates

2010

The formation of protein aggregates is important in many fields of life science and technology. The morphological and mechanical properties of protein solutions depend upon the molecular conformation and thermodynamic and environmental conditions. Non-native or unfolded proteins may be kinetically trapped into irreversible aggregates and undergo precipitation or gelation. Here, we study the thermal aggregation of lysozyme in neutral solutions. We characterise the irreversible unfolding of lysozyme by differential scanning calorimetry. The structural properties of aggregates and their mechanisms of formation with the eventual gelation are studied at high temperature by spectroscopic, rheolog…

Detection of Hypoxanthine from Inosine and Unusual Hydrolysis of Immunosuppressive Drug Azathioprine through the Formation of a Diruthenium(III) Syst…

2021

Hypoxanthine (hpx) is an important molecule for both biochemistry research and biomedical applications. It is involved in several biological processes associated to energy and purine metabolism and has been proposed as a biomarker for a variety of disease states. Consequently, the discovery and development of systems suitable for the detection of hypoxanthine is pretty appealing in this research field. Thus, we have obtained a stable diruthenium (III) compound in its dehydrated and hydrated forms with formula [{Ru(&micro

Syntheses and structural study of bile acid amidoalcohols.

2008

Preparation, structural and thermoanalytical characterization of fourteen N-hydroxyalkyl 5beta-cholan-24-amides have been performed in this study. The utilized techniques include liquid state and CP-MAS 13C NMR spectroscopy, thermogravimetry, differential scanning calorimetry, and also powder and single crystal X-ray crystallography. The results were discussed and compared to each other and also to previous findings on similar compounds. One pure hydrate form was obtained. Six new single crystal structures were determined, including one hydrated chloroform solvate. Decomposition temperatures were found to correlate with the side chain length, and the number of the hydroxyl groups. The spati…

Calorimetric Behavior of Phosphatidylcholine/Phosphatidylethanolamine Bilayers is Compatible with the Superlattice Model

2012

Differential scanning calorimetry was used to study the phase behavior of binary lipid bilayers consisting of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) of varying acyl chain length. A two-state transition model was used to resolve the individual transition components, and the two-state transition enthalpy, the relative enthalpy, and the transition temperature of each component were plotted as a function of composition. Intriguingly, abrupt changes in these thermodynamic parameters were observed at or close to many "critical" X(PE) values predicted by the superlattice model proposing that phospholipids with different headgroups tend to adopt regular rather than random latera…

Structural and Molecular Characterization of meso-Substituted Zinc Porphyrins: A DFT Supported Study

2011

Structural parameters of a range of over 100 meso-substituted zinc porphyrins were reviewed and compared to show how far the nature of the functional group may affect the interatomic distances and bond angles within the porphyrin core. It was proved that even despite evident deformations of the molecular structure, involving twisting of the porphyrin's central plane, the coupled π-bonding system remains flexible and stable. DFT calculations were applied to a number of selected porphyrins representative for the reviewed compounds to emphasize the relevance of theoretical methods in structural investigations of complex macrocyclic molecular systems. Experimental and DFT-simulated IR spectral …

Reactive blending of a functionalized polyethylene with a semiflexible liquid crystalline copolyester

1996

Reactive blends (50/50 w/w) of a low molar mass polyethylene containing free carboxylic groups (PEox) and a semiflexible liquid crystalline polyester (SBH 1 : 1 : 2, by Eniricerche) have been prepared at 240 degrees C in a Brabender mixer, in the presence of Ti(OBu)(4) catalyst, for different mixing times (15, 60, and 120 min). In order to prove the formation of a PE-g-SBH copolymer, the blends have been fractionated by successive extractions with boiling toluene and xylene. The soluble fractions and the residues have been analyzed by Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG and DTG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM)…

Reactive compatibilization of PA6/LDPE blends with an ethylene–acrylic acid copolymer and a low molar mass bis-oxazoline

2003

Abstract A sample of polyamide-6 (PA) was blended with low density polyethylene (LDPE) in the 80/20 wt/wt ratio, either without and with 2 phr of an ethylene–acrylic acid copolymer (EAA), Which was known to behave as a compatibilizer precursor, and the effect of the addition of small amounts (0.2 or 0.35 phr) of a fourth component, 2,2′-(1,3-phenylene)-bis(2-oxazoline) (PBO), was investigated. The reactions of PBO with EAA, PA and their blends were studied by recording as a function of time the torque applied to the blending apparatuses and by studying the solubility behavior of the products in formic acid. The PALDPE blends were prepared in a co-rotating twin screw extruder and were charac…

1995

About 340 g of a cycloaliphatic ionene (see formula given in the introduction) were fractionated by a continuous countercurrent extraction method (CPF). The efficiency of the separation was checked by viscometry and gel permeation chromatography (GPC). Ten different fractions with number average molecular masses between 16 000 and 29 000 D were obtained and their glass transition temperatures T g determined by differential scanning calorimetry (DSC) for their bromide and tetrafluoroborate salts. No molecular weight dependence of T g was found, in contrast to recently reported results with aliphatic ionenes, where - in case of the bromide - T g increases with rising molecular weight.

Effect of diode laser irradiation on the attachment rate of periodontal ligament cells: an in vitro study.

2001

The present study is part of a basic research program investigating the cellular effects of an 810 nm GaAlAs-diode laser on human periodontal tissues. The aim of the investigation was to evaluate the effects of laser treatment of root surface specimens on the attachment of periodontal ligament (PDL) cells in vitro.Root specimens were prepared from periodontally diseased teeth. PDL cells were obtained from human third molar ligaments. Cells were cultured under simple, standardized, and reproducible experimental conditions. One hundred fifty root specimens were scaled and root planed with curets followed by air-powder abrasive treatment; 75 were then lased and 75 served as controls. The irrad…