Authors:Katarzyna Michalik, Zofia Drzazga, and Anna Michnik
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.
Authors:Anna Michnik, Katarzyna Michalik, and Zofia Drzazga
Summary The effect of pH on the thermal denaturation of BSA containing fatty acids was studied by use of differential scanning calorimetry (DSC). Thermal scanning of BSA aqueous solutions gave various types of DSC curves depending on the protein concentration and on the pH. The broad bimodal endothermic transition was suggested to be connected with loose protein structure in contradistinction to single peak for compact molecule structure. The propensity toward precipitation at pH conditions ranging from 3.8 to 5 was observed. A scan-rate independent and partly reversible behavior of the thermal heating of BSA was found. Deconvolution of DSC traces in non-two-state model with assumption of two- or three-component transition allowed to study the effect of pH on different parts of BSA molecule.
Authors:Zofia Drzazga, Katarzyna Michalik, Tomasz Halat, Anna Michnik, and Henryk Trzeciak
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 Cpex 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.
Authors:Katarzyna Michalik, Zofia Drzazga, Anna Michnik, and M. Kaszuba
and kinetic analysis of two protease inhibitors: nelfinavir mesylate and atazanavir
sulfate, were carried out to find their thermal stability. DSC curves of both
drugs showed exothermic transition. This observed process resulted in two
steps. Obtained apparent activation energy pointed at low stability of studied
protease inhibitors in water solutions.