Search Results

You are looking at 1 - 6 of 6 items for :

  • "differential scanning microcalorimetry" x
  • All content x
Clear All

Abstract  

A differential scanning calorimetry study of the thermal behavior of nevirapine and azidothymidine in water solution was carried out. For nevirapine scan rate dependent and irreversible endothermic peak were found. Thermal degradation of nevirapine as well as NVP – AZT mixture is relatively well described by the model involving only one irreversible step determined by a first-order rate constant. The estimated kinetic constants and activation energies indicate that the degradation process proceeds slower for nevirapine in presence of AZT ligands than without them.

Restricted access

Calorimetric characterization of 2′,3′-dideoxyinosine water solution

Stability and interaction with human serum albumin

Journal of Thermal Analysis and Calorimetry
Authors: Katarzyna Michalik, Zofia Drzazga, and Anna Michnik

Abstract  

A study of 2′,3′-dideoxyinosine (ddI) stability and its interaction with human serum albumin (HSA) was carried out by differential scanning microcalorimetry DSC. Scan rate dependent and irreversible endothermic thermal degradation of ddI was analyzed with use of kinetic approach. Observed process could be interpreted in terms of simple first-order one step kinetic model. Moreover it was shown that ddI bound weakly to the human serum albumin and stabilized this protein.

Restricted access

Abstract  

Interactions of anionic surfactant sodium dodecyl sulphate (SDS) with vesicles formed by synthetic dialkyldimethylammonium bromides i.e. didodecyldimethylammonium bromide (DDAB), ditetradecyldimethylammonium bromide (DTAB), dihexadecyldimethylammonium bromide (DHAB) have been examined by using differential scanning microcalorimetry and electron transmission microscopy. The temperatures and standard enthalpies characterising gel to liquid-crystal transitions increase significantly with increase of SDS concentration for all investigated systems. It means that incorporation of SDS monomers in these vesicular bilayers significantly stabilises their gel states. Moreover, in case of DDAB and DTAB vesicle systems added SDS limits kinetic features of recorded isobaric heat capacity dependencies on temperature observed earlier for the pure vesicular solutions.

Restricted access

Abstract  

Differential scanning microcalorimetry and equilibrium thermohemolysis procedure were used to study the effect of acclimation temperature on thermally induced transitions and thermoresistivity of fish (trout) erythrocyte membranes. Strong correlation has been found between the rates and activation energies of erythrocyte thermohemolysis and acclimation temperature. Transition temperatures of five thermodynamically irreversible and one partially reversible transitions at about 87C as well as the overall shape of microcalorimetric curves of the erythrocyte ghosts do not vary with acclimation temperature. The results suggest an essential conservation of phospholipid microenvironment of membrane skeleton proteins despite the compensatory response in lipid composition of erythrocyte membrane bilayer.

Restricted access

Abstract  

The interaction of chitosan and its N-dodecyl and poly(ethylene glycol) derivatives with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) vesicles was studied to evaluate the influence of molecular architecture of the polymers on the liposomes. The study was carried out in aqueous solution using differential scanning microcalorimetry (DSC) and dynamic light scattering. The interaction of these polymers with DPPC vesicles altered the gel–liquid crystalline phase transition temperature and decreased both the enthalpy (ΔH) and cooperativity of the phase transition. The results obtained indicate that perturbations in the vesicles surface and the incorporation of chitosan and its derivatives into the lipid bilayer upon polysaccharides interaction are responsible for the formation of large vesicles.

Restricted access

Abstract  

Differential scanning microcalorimetry (DSC) and UV–VIS absorption spectroscopy were used to obtain the characteristics of blood serum from newborn rat’ after maternal treatment with cyclophosphamide in comparison with control. The obtained DSC curves reveal a complex endothermic peak due to the unfolding process of various serum proteins. Thermal profiles and absorption spectra of blood serum are sensitive to the age of newborns as well as to effect of maternal administration of cyclophosphamide. The most significant disturbances in serum proteome were observed for 14-day old newborns. The thermodynamic parameters: enthalpy change (∆H), the normalized first moment (M1) of the thermal transition with respect to the temperature axis and the ratio of C p ex at 70 and 60 °C describing denaturation contributions of globulin forms in respect to unliganded albumin with haptoglobin was estimated. Moreover, the second derivative spectroscopy in the UV region was used to resolve the complex protein spectrum. The differences in blood serum detected by DSC and UV–VIS confirm a potential usefulness of these methods for diagnostic and monitoring changes with age as well as the pathological state of blood serum.

Open access