80 research outputs found
Predicting Discounts of Secondary Market Sovereign Debts
This paper assesses the Institutional Investor Country Risk Rating (IICR) to analyze whether secondary market prices are reliable indicators of debt values. It starts with the conviction that the rating scores are reasonable measure of banker’s perceptions of the country’s creditworthiness. Regression results indicate illiquidity of the secondary market.risk
Predicting Discounts of Secondary Market Sovereign Debts
This paper assesses the Institutional Investor Country Risk Rating (IICR) to analyze whether secondary market prices are reliable indicators of debt values. It starts with the conviction that the rating scores are reasonable measure of banker’s perceptions of the country’s creditworthiness. Regression results indicate illiquidity of the secondary market.risk
Neural adaptations to electrical stimulation strength training
This review provides evidence for the hypothesis that electrostimulation strength training (EST) increases the force of a maximal voluntary contraction (MVC) through neural adaptations in healthy skeletal muscle. Although electrical stimulation and voluntary effort activate muscle differently, there is substantial evidence to suggest that EST modifies the excitability of specific neural paths and such adaptations contribute to the increases in MVC force. Similar to strength training with voluntary contractions, EST increases MVC force after only a few sessions with some changes in muscle biochemistry but without overt muscle hypertrophy. There is some mixed evidence for spinal neural adaptations in the form of an increase in the amplitude of the interpolated twitch and in the amplitude of the volitional wave, with less evidence for changes in spinal excitability. Cross-sectional and exercise studies also suggest that the barrage of sensory and nociceptive inputs acts at the cortical level and can modify the motor cortical output and interhemispheric paths. The data suggest that neural adaptations mediate initial increases in MVC force after short-term EST
Overexpression, purification, crystallisation and preliminary structural study of dTDP-6-deoxy-lyxo-4-reductase (RmlD) the fourth enzyme of the dTDP-rhanose synthesis pathway, from <i>Salmonella entrica</i> serovar Typhimurim
L-Rhamnose is an essential component of the cell wall of many pathogenic bacteria. Its precursor, dTDP-L-rhamnose, is synthesized from cr-D-glucose-l-phosphate and dTTP via a pathway requiring four distinct enzymes: RmlA, RmlB, RmlC and RmlD. RmlD catalyses the terminal step of this pathway by converting dTDP-6-deoxy-L-lyxo-4-hexulose to dTDP-L-rhamnose. RmlD from Salmonella enterica serovar Typhimurium has been overexpressed in Escherichia coli. The recombinant protein was purified by a two-step protocol involving anion-exchange and hydrophobic chromatography. Dynamic light-scattering experiments indicated that the recombinant protein is monodisperse. Crystals of native and selenomethionine-enriched RmlD have been obtained using the sitting-drop vapour-diffusion method with polyethylene glycol as precipitant. Diffraction data have been collected from orthorhombic crystals of both native and selenomethionyl-derivatized protein, allowing tracing of the protein structure.</p
Overexpression, purification, crystallisation and preliminary structural study of dTDP-6-deoxy-lyxo-4-reductase (RmlD) the fourth enzyme of the dTDP-rhanose synthesis pathway, from <i>Salmonella entrica</i> serovar Typhimurim
L-Rhamnose is an essential component of the cell wall of many pathogenic bacteria. Its precursor, dTDP-L-rhamnose, is synthesized from cr-D-glucose-l-phosphate and dTTP via a pathway requiring four distinct enzymes: RmlA, RmlB, RmlC and RmlD. RmlD catalyses the terminal step of this pathway by converting dTDP-6-deoxy-L-lyxo-4-hexulose to dTDP-L-rhamnose. RmlD from Salmonella enterica serovar Typhimurium has been overexpressed in Escherichia coli. The recombinant protein was purified by a two-step protocol involving anion-exchange and hydrophobic chromatography. Dynamic light-scattering experiments indicated that the recombinant protein is monodisperse. Crystals of native and selenomethionine-enriched RmlD have been obtained using the sitting-drop vapour-diffusion method with polyethylene glycol as precipitant. Diffraction data have been collected from orthorhombic crystals of both native and selenomethionyl-derivatized protein, allowing tracing of the protein structure.</p
Characterisation of the structure of ocr, the gene 0.3 protein of bacteriophage T7
The product of gene 0.3 of bacteriophage T7, ocr, is a potent inhibitor of type I DNA restriction and modification enzymes. We have used biophysical methods to examine the mass, stability, shape and surface charge distribution of ocr. Ocr is a dimeric protein with hydrodynamic behaviour equivalent to a prolate ellipsoid of axial ratio 4.3 ± 0.7:1 and mass of 27 kDa. The protein is resistant to denaturation but removal of the C-terminal region reduces stability substantially. Six amino acids, N4, D25, N43, D62, S68 and W94, are all located on the surface of the protein and N4 and S68 are also located at the interface between the two 116 amino acid monomers. Negatively charged amino acid side chains surround W94 but these side chains are not part of the highly acidic C-terminus after W94. Ocr is able to displace a short DNA duplex from the binding site of a type I enzyme with a dissociation constant of the order of 100 pM or better. These results suggest that ocr is of a suitable size and shape to effectively block the DNA binding site of a type I enzyme and has a large negatively charged patch on its surface. This charge distribution may be complementary to the charge distribution within the DNA binding site of type I DNA restriction and modification enzymes
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