Search results for "GOME"
showing 10 items of 329 documents
Study of thermal properties of polyethylene and polypropylene nanocomposites with long alkyl chain-substituted POSS fillers
2016
The effect of incorporation of octakis({alkyl}dimethylsiloxy)octasilsesquioxanes molecules with n-octyl, n-octadecyl and 4-methyl-hexyl substituents on thermal properties of polypropylene (PP), low-density polyethylene (LDPE) and high-density polyethylene (HDPE) was investigated. Thermal properties of those composite materials were evaluated by means of the differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) methods. The type and mass% content of POSS nanofillers influenced the crystallization and melting properties as well as thermal stability of the obtained polyolefin nanocomposites. The incorporated POSS particles—acting as nucleating agents—improved the crystall…
Correct oligomerization is a prerequisite for insertion of the central molecular domain of staphylococcal α-toxin into the lipid bilayer
1995
Staphylococcal alpha-toxin is a primarily hydrophilic molecule that binds as a monomer to target membranes and then aggregates to form amphiphilic oligomers that represent water-filled transmembrane channels. Current evidence indicates that a region located in the center of the molecule inserts deeply into the bilayer. In the present study, we sought to determine whether membrane insertion was triggered by the oligomerization process, and whether insertion correlated with pore formation. Double mutants of alpha-toxin were prepared in which His-35 was replaced by Arg, and cysteine residues were introduced at positions 69, 130 and 186. Substitution of His-35 with Arg rendered the toxin molecu…
Cholesterol Specificity of Some Heptameric β-Barrel Pore-Forming Bacterial Toxins: Structural and Functional Aspects
2010
Apart from the thiol-specific/cholesterol-dependent cytolysin family of toxins (see Chapter 20) there are a number of other unrelated bacterial toxins that also have an affinity for plasma membrane cholesterol. Emphasis is given here on the Vibrio cholerae cytolysin (VCC) and the cytolysins from related Vibrio species. The inhibition of the cytolytic activity of these toxins by prior incubation with extracellular cholesterol or low density lipoprotein emerges as a unifying feature, as does plasma membrane cholesterol depletion. Incubation of VCC with cholesterol produces a heptameric oligomer, which is not equivalent to the pre-pore since it is unable to penetrate the plasma membrane. In st…
Tre osservazioni su diez tesis acerca de la coherencia en el Derecho
2021
El artículo está dedicado a tres observaciones críticas sobre la concepción de la coherencia defendida por Amaya. Estas observaciones se refieren a: a) la supuesta incompatibilidad entre la coherencia y la concepción instrumental de la razón práctica; b) la aspiración a la best explanation y, finalmente, c) al vínculo entre la coherencia y la responsabilidad epistémica.
Mutational analyses of YqjA, a Tvp38/DedA protein of E. coli
2015
AbstractMembrane proteins of the DedA/Tvp38 protein family are involved in membrane integrity and virulence of pathogenic organisms. However, the structure and exact function of any member of this large protein family are still unclear. In the present study we analyzed the functional and structural properties of a DedA homolog. Purified YqjA variants from Escherichia coli are detectable in different oligomeric states and specific homo-interaction of YqjA monomers in the membrane were confirmed by formation of a disulfide bond in the C-terminal transmembrane helix. Moreover, alanine scanning mutagenesis exhibited different interaction sites crucial for YqjA activity vs. dimer formation.
Human apolipoprotein A-I natural variants: molecular mechanisms underlying amyloidogenic propensity
2012
Human apolipoprotein A-I (apoA-I)-derived amyloidosis can present with either wild-type (Wt) protein deposits in atherosclerotic plaques or as a hereditary form in which apoA-I variants deposit causing multiple organ failure. More than 15 single amino acid replacement amyloidogenic apoA-I variants have been described, but the molecular mechanisms involved in amyloid-associated pathology remain largely unknown. Here, we have investigated by fluorescence and biochemical approaches the stabilities and propensities to aggregate of two disease-associated apoA-I variants, apoA-IGly26Arg, associated with polyneuropathy and kidney dysfunction, and apoA-ILys107-0, implicated in amyloidosis in severe…
Interacting induced dipoles polarization model for molecular polarizabilities: application to benzothiazole (A)-benzobisthiazole (B) oligomers AB13A
1998
Abstract We have outlined a method for the calculation of atomic net charges and molecular dipole-dipole, α , dipole-quadrupole, A , and quadrupole-quadrupole, C , polarizabilities which we have successfully applied to benzothiazole (A)-benzobisthiazole (B) oligomers in the series AB1A to AB13A, and the results have been extrapolated to give predictions for polybenzobisthiazole. The calculation of α , A and C has been carried out by the interacting induced dipoles polarization model that calculates tensor effective anisotropic point polarizabilities (method of Applequist). The mean effective atomic αeffpolarizabilities for the monomeric unit are of the same order of magnitud…
GENETIC AND ENVIRONMENTAL VARIATION IN PERCEIVED EXERTION AND HEART RATE DURING BICYCLE ERGOMETER WORK
1977
The relative contributions of heredity and environment to the variance in heart rate (HR) and rating of perceived exertion (RPE) during the bicycle ergometer work were studied with 14 pairs of male (6 monozygous (MZ) and 8 dizygous (DZ)) and 22 pairs of female (8 MZ and 14 DZ) twins ranging in age from 11 to 20 years. The results showed for both sexes that no significant differences in the intrapair variances of HR and RPE could be observed between the MZ and DZ twin samples. Thus it was concluded that in contrast to several other parameters of the measurements of the physical work capacity HR and RPE are not influenced to any significant degree by the genetic factors.
Kinetics of streptolysin O self-assembly.
1995
Streptolysin O is a member of a family of membrane-damaging toxins that bind to cell membranes containing cholesterol and then polymerize to form large pores. We have examined the kinetics of toxin action using 125I-labelled streptolysin O. Binding of toxin monomers to membranes displays first-order kinetics and is reversible; the rate of desorption from red cells shows a marked dependence on temperature. To study oligomerization, toxin was bound to erythrocytes at 0 degrees C. Oligomer formation was then triggered by a sudden temperature shift and stopped by solubilization of membranes with deoxycholate. While at moderately high streptolysin O concentrations oligomerization behaves as a re…
Dithiol-Induced Oligomerization of Thiol-Protected Gold Nanoclusters
2018
Controlled synthesis of nanostructure oligomers requires detailed understanding of their wet chemistry and the forces driving the polymerization process. In this paper, we report the main factors affecting the reaction yields of a dithiol-induced synthesis of covalently bound nanocluster dimers and oligomers and present a detailed analysis of possible reaction mechanisms. We synthesize the nanocluster oligomers using monodisperse para-mercaptobenzoic acid (p-MBA)-protected gold nanoclusters with a nominal composition of Au∼250(p-MBA)n to minimize ensemble effects on size, shape, and surface structure. Ligand exchange was performed on the nanoclusters with five different dithiol linkers: 5,5…