Search results for "denaturation"

STATISTICAL MECHANICS OF NONCLASSIC SOLITONIC STRUCTURES-BEARING DNA SYSTEM

2011

We theoretically investigate the thermodynamic properties of modified oscillator chain proposed by Peyrard and Bishop. This model obtained by adding the quartic anharmonicity term to the coupling in the Peyrard–Bishop model is useful to model the coexistence of various phases of the molecule during the denaturation phenomenon. Within the model, the negative anharmonicity is responsible for the sharpness of calculated melting curves. We perform the transfer integral calculations to demonstrate that the model leads to a good agreement with known experimental results for DNA.

A family with various symptomatology suggestive of Anderson-Fabry disease and a genetic polymorphism of alpha galactosidase A gene.

2014

Background: Anderson/Fabry disease expresses a wide range of clinical variability in patients that it is possible to explain referring to a genetic variability with numerous mutations described in the literature (more than 600). Methods: We report some clinical cases of some members of a Sicilian family to express phenotypical variability of this disease in subjects with the same genetic mutation. Results: The first case was a 59-year-old female. Brain MRI revealed right frontal periventricular white matter of likely vascular-degenerative origin. The proband's alpha galactosidase A activity was 3.7. nmol/mL/h. Molecular genetics revealed a polymorphism: - 10 C. >. T; IVS 2-76_80del5; IVS…

Molecular mass of macromolecules and subunits and the quaternary structure of hemoglobin from the microcrustacean Daphnia magna

2006

The molecular masses of macromolecules and subunits of the extracellular hemoglobin from the fresh-water crustacean Daphnia magna were determined by analytical ultracentrifugation, multiangle laser light scattering and electrospray ionization mass spectrometry. The hemoglobins from hypoxia-incubated, hemoglobin-rich and normoxia-incubated, hemoglobin-poor Daphnia magna were analyzed separately. The sedimentation coefficient of the macromolecule was 17.4 +/- 0.1 S, and its molecular mass was 583 kDa (hemoglobin-rich animals) determined by AUC and 590.4 +/- 11.1 kDa (hemoglobin-rich animals) and 597.5 +/- 49 kDa (hemoglobin-poor animals), respectively, determined by multiangle laser light sca…

Conformational changes involved in thermal aggregation processes of bovine serum albumin

2003

We report a kinetic study on thermal aggregation process of the model protein bovine serum albumin (BSA) in low concentration regime. Aim of this study is to provide information on relationship between conformational changes and initial step of aggregation. The experimental approach is based on steady-state fluorescence spectra of the two tryptophans located in two different domains, in way to study conformational changes in the surrounding of these residues. We also follow emission spectra of Fluorescein-5-Maleimide dye bound to the single free cysteine of BSA. Complementary information on the extent of aggregation and on the structural changes is obtained by Rayleigh scattering and circul…

Thermal denaturation of myoglobin in water--disaccharide matrixes: relation with the glass transition of the system.

2009

Proteins embedded in glassy saccharide systems are protected against adverse environmental conditions [Crowe et al. Annu. Rev. Physiol. 1998, 60, 73-103]. To further characterize this process, we studied the relationship between the glass transition temperature of the protein-containing saccharide system (T(g)) and the temperature of thermal denaturation of the embedded protein (T(den)). To this end, we studied by differential scanning calorimetry the thermal denaturation of ferric myoglobin in water/disaccharide mixtures containing nonreducing (trehalose, sucrose) or reducing (maltose, lactose) disaccharides. All the samples studied are, at room temperature, liquid systems whose viscosity …

Immunological analyses of human papillomavirus capsids

2001

Recombinant human papillomavirus (HPV) virus-like particles (VLPs) are promising vaccine candidates for controlling anogenital HPV disease. Questions remain, however, concerning the extent of capsid antigenic similarity between closely related virus genotypes. To investigate this issue, we produced VLPs and corresponding polyclonal immune sera from several anogenital HPV types, and examined these reagents in enzyme-linked immunosorbent assays (ELISAs) and in cross-neutralization studies. Despite varying degrees of L1 genetic sequence relatedness, VLPs of each type examined induced high-titer serum polyclonal antibody responses that were entirely genotype-specific. In an in vitro infectivity…

Production of biologically active recombinant avidin in baculovirus-infected insect cells

1997

Abstract An efficient lepidopteran insect cell system was established for the expression of a recombinant form of chicken egg-white avidin. The gene product was obtained in both secreted and intracellular forms, and biologically active recombinant avidin was isolated using affinity chromatography on an iminobiotin–agarose column. Similar to the known quaternary structure of the native egg-white protein, the purified recombinant protein was glycosylated and assembled mainly into tetramers. Like native avidin, the recombinant tetramer also exhibited a high level of thermostability, and was further stabilized upon binding biotin. The biotin-binding and structural properties of the recombinant …

Thermal aggregation of beta-lactoglobulin in presence of metal ions.

2007

In this work, we report a study of the effects of zinc and copper ions on the heat-induced aggregation of beta-lactoglobulin (BLG). Kinetics investigations on aggregates growth by light scattering measurements and on secondary structure changes by FTIR absorption measurements show the different role played by the two metals during the whole process. In particular, the presence of zinc in solution promotes the formation of aggregates of BLG at a lower temperature than copper. Then, at fixed temperature, formation of a large amount of aggregates, of large dimension, is observed for Zn-BLG in shorter time; on the contrary, the presence of copper in solution does not affect the aggregation proc…

Thin-layer affinity chromatography in analysis of protein-ligand affinity.

1996

Inhibition of prolyl hydroxylation and procollagen processing in chick-embryo calvaria by a derivative of pyridine-2,4-dicarboxylate. Characterizatio…

1991

The biochemical and morphological consequences of procollagen prolyl 4-hydroxylase inhibition by pyridine-2,4-dicarboxylic acid (2,4-PDCA) and its diethyl ester (diethyl-2,4-PDC) were studied in chick-embryo calvaria, which predominantly synthesize type I collagen. Half-maximal inhibition of tissue hydroxyproline formation required 650 microM-2,4-PDCA, whereas the Ki with respect to chicken prolyl 4-hydroxylase in vitro was 2 microM. In contrast, half-maximal inhibition was caused by 10 microM-diethyl-2,4-PDC in the intact calvaria, although chicken prolyl 4-hydroxylase in vitro was not inhibited even at 1 mM. The collagenous material produced in the presence of diethyl-2,4-PDC showed an al…