PROBLEME DER ZEITGEMÄSSEN BEMESSUNG VON FÖRDERTECHNISCHEN MASCHINEN

In mammals, small heat-shock proteins (sHSPs) typically assemble into interconverting, polydisperse oligomers. The dynamic exchange of sHSP oligomers is regulated, at least in part, by molecular interactions between the α-crystallin domain and the C-terminal region (CTR). Here we report solution-state nuclear magnetic resonance (NMR) spectroscopy investigations of the conformation and dynamics of the disordered and flexible CTR of human HSP27, a systemically expressed sHSP. We observed multiple NMR signals for residues in the vicinity of proline 194, and we determined that, while all observed forms are highly disordered, the extra resonances arise from cis-trans peptidyl-prolyl isomerization about the G193-P194 peptide bond. The cis-P194 state is populated to near 15% at physiological temperatures, and, although both cis- and trans-P194 forms of the CTR are flexible and dynamic, both states show a residual but differing tendency to adopt β-strand conformations. In NMR spectra of an isolated CTR peptide, we observed similar evidence for isomerization involving proline 182, found within the IPI/V motif. Collectively, these data indicate a potential role for cis-trans proline isomerization in regulating the oligomerization of sHSPs

Analysing protein competition on self-assembled mono-layers studied with quartz crystal microbalance

The mechanisms by which proteins adsorb to surfaces of biomaterials have long been of interest. The present work started with the premise that small/hard and large/soft proteins will yield different sets of normalized frequency shift and dissipation signals when studied with a quartz crystal microbalance. The aim was to evaluate the usefulness of these raw data to study protein competition using protein incubations in sequence and from mixtures of albumin (BSA) and gamma-globulin (BGG) at various ratios. Increasing the concentration of BSA decreases the adsorption of subsequently incubated BGG. For BSA/ BGG mixtures the dissipation is similar for all logarithmic molar ratios BGG/BSA below 1 but soon decreases when the molar ratio of BSA/BGG (and opposite for the normalized frequency shift) is above 1, indicating preferential binding of BGG. Modelling indicated that differences in the film shear modulus and viscosity depend more on the properties of the self-assembling mono-layers (SAMs) than on the proteins. Films high in BSA tentatively differ in film shear modulus and viscosity from that of films high in BGG but only on the hydrophobic surfaces. The results were encouraging as the raw data were deemed to be able to point at protein adsorption competition.The authors thank the Portuguese National Science and Technology Foundation (FCT) for the Project Grants PTDC/FIS/68517/2006 and PTDC/FIS/68209/2006, and personal Grant BPD/39331/2007 for J.B

Collision cross sections of high-mannose N-glycans in commonly observed adduct states – identification of gas-phase conformers unique to [M − H]^- ions

We report collision cross sections (CCS) of high-mannose N-glycans as [M + Na]+, [M + K]+, [M + H]+, [M + Cl]-, [M + H2PO4]- and [M − H]- ions, measured by drift tube (DT) ion mobility-mass spectrometry (IM-MS) in helium and nitrogen gases. Further analysis using traveling wave (TW) IM-MS reveal the existence of distinct conformers exclusive to [M − H]- ions

Morphology and miscibility of chitosan/soy protein blended membranes

A physico-chemical characterization of blended membranes composed by chitosan and soy protein has been carried out in order to probe the interactions that allow membranes to be formed from these biopolymer mixtures. These membranes are developed aiming at applications in wound healing and skin tissue engineering scaffolding. The structural features of chitosan/soy blended membranes were investigated by means of solid state carbon nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR), contact angle, and atomic force microscopy. FTIR investigations suggested that chitosan and soy may have participated in a specific intermolecular interaction. The proton spin–lattice relaxation experiments in the rotating frame on blended membranes indicated that independently of the preparation conditions, the blend components are not completely miscible possibly due to a weak polymer–protein interaction. It was also shown that the blended systems showed a rougher surface morphology which was dependent of soy content in the blend system

Correlation of a solar flare with a visual aurora

Correlation of solar flare with visual auror

Application of fluorescence techniques to the study of protein adsorption and packing on biomaterial surfaces

[Excerpt] The ways proteins compete for the surface of biomaterials and change conformation are believed to be important for the host response to implants. It is possible to elucidate information on packing and any induced conformational change by making use of different fluorescence techniques on fluorescently labelled proteins. Employing probe-probe resonance energy transfer (RET) allows inter and intra protein interactions to be distinguished. Homo resonance energy transfer (hRET) avoids many problems with having two different probes and means that labelling and subsequent purification can be done in one step. [...]Portuguese Foundation for Science and Technology, project PROTEOLIGHT (PTDC/FIS/68517/2006) and J.B. grant SFRH/BPD/17584/2004. European Union NoE EXPERTISSUES (NMP3-CT-2004-500283) and European Union FP6 STREP project HIPPOCRATES (NMP3-CT-2003-505758).info:eu-repo/semantics/publishedVersio

Fluorescence probe techniques to monitor protein adsorption-induced conformation changes on biodegradable polymers

The study of protein adsorption and any associated conformational changes on interaction with biomaterials is of great importance in the area of implants and tissue constructs. This study aimed to evaluate some fluorescent techniques to probe protein conformation on a selection of biodegradable polymers currently under investigation for biomedical applications. Because of the fluorescence emanating from the polymers, the use of monitoring intrinsic protein fluorescence was precluded. A highly solvatochromic fluorescent dye, Nile red, and a well-known protein label, fluorescein isothiocyanate, were employed to study the adsorption of serum albumin to polycaprolactone and to some extent also to two starch-containing polymer blends (SPCL and SEVA-C). A variety of fluorescence techniques, steady state, time resolved, and imaging were employed. Nile red was found to leach from the protein, while fluorescein isothiocyanate proved useful in elucidating a conformational change in the protein and the observation of protein aggregates adsorbed to the polymer surface. These effects were seen by making use of the phenomenon of energy migration between the fluorescent tags to monitor interprobe distance and the use of fluorescence lifetime imaging to ascertain the surface packing of the protein on polymer

Beam Correction for Multi-Pass Arcs in FFA@ CEBAF: Status Update

As design and simulation studies for the energy upgrade at the Continuous Electron Beam Accelerator Facility progress, both static and dynamic errors must be addressed. The current upgrade design introduces a pair of Fixed-Field Alternating-Gradient (FFA) recirculating arcs: one in the East recirculating arc, and one in the West. In the present design, each FFA arc supports six concurrent beam energies in the same beam pipe; these must be concurrently corrected for both static and dynamic errors. This document discusses the present beam correction strategies applied in simulation

Jefferson Lab IR FEL cryomodule modifications and test results

The Infrared Free Electron Laser being constructed at the Thomas Jefferson National Accelerator Facility will require a 42 MeV, 5 mA electron accelerator. The accelerator design requires a 10 MeV injector and a two pass 32 MeV linac, one pass for acceleration and one pass for energy recovery. In order to minimize the cost of the linac, standard CEBAF 1497 MHZ Superconducting Radio Frequency cavities and cryomodules are being used with minimal changes. Two SRF cavities, housed in a quarter cryomodule, operate at a nominal 10 MV/m to provide the injector energy. The linac is composed of one cryomodule, housing eight SRF cavities operating at an average gradient of 8 MV/m. The modifications to the cryomodule are being made to handle the higher beam current, to improve RF control, and to increase machine reliability. The modifications to the higher order mode (HOM) loads, cavity tuners, cavity beam line, warm and cold RF windows, and cryogenic shield are described. Test results from the injector quarter cryomodule are also presented