A calorimetric study of thermal denaturation of bovine serum albumin in aqueous solutions has shown essential differences
in stability of fatty acid containing and defatted albumin. The first one shows a single endotherm peak in DSC curve near
69°C with enthalpy change about 1000 kJ mol-1. Defated albumin melts in two different temperature ranges: near 56 and 69°C with enthalpy changes about 300 and 200 kJ mol-1 respectively. Deconvolution analysis shows that the single endotherm is well approximated as the sum of three independent
two-state transitions. Two transitions of bimodal DSC curve for defatted albumin are not of a two-state type. This molecule
melts probably as two structurally independent parts.
Authors:Anna Michnik, Aleksandra Kłos, and Zofia Drzazga
Protein unfolding events were studied by differential scanning calorimetry (DSC) for bovine serum albumin (BSA) aqueous solutions
exposed to radio-frequency radiation. No immediate effect of this radiation on thermal unfolding of BSA was observed. The
differences between irradiated and control samples have appeared during the storage of BSA solution. The irradiated samples
changed faster than non-irradiated. Our results indicated that the age-related changes were stronger for 3.5 and 5 MHz than
for 247 MHz frequency and dependent on energy power of radiation. Deconvolution of DSC traces allowed to study the effect
of radio-frequency radiation on each component transition.
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:Anna Michnik, K. Michalik, A. Kluczewska, and Zofia Drzazga
The thermal denaturation process of bovine and human
both fatty acid containing and fatty acid free albumins in aqueous solution
was studied by use of differential scanning calorimetry. Human serum albumins
were found to be more stable than their bovine counterparts. Fatty acid free
albumins were characterized as generally less stable, more susceptible to
aggregation, their unfolding endothermic transition was less cooperative and
with the smaller degree of reversibility. Deconvolution analysis with using
a non-two-state model with two component transitions showed essential differences
in the thermodynamic parameters between all studied albumins, particularly
regarding the high-temperature component transition.
available since several companies have produced their own instruments. Herein, we summarized our own efforts on purification of six natural quinolone alkaloids from T. ruticarpum ( Figure 1 ) and evaluated their binding affinity for bovineserumalbumin
Authors:J. Németh, G. Oroszi, B. Jakab, M.i Magyarlak, Z. Szilvassy, E. Rőth, and B. Farkas
The iodination and separation of various diagnostically and/or experimentally important peptides including (Tyr1)-somatostatin-14, rat Tyr-a-calcitonin gene-related peptide (23-37), motilin and vasoactive intestinal peptide, furthermore bovine serum albumin are described. All species were iodinated by the iodogen method. The 125I-labeled peptide products were separated by reversed-phase HPLC, the specific activities of mono-iodinated forms are near identical with the theoretical value. The labeled bovine serum albumin was separated by Sephadex G-100 gel filtration.
Authors:G. Barone, S. Capasso, P. Del Vecchio, C. De Sena, D. Fessas, C. Giancola, G. Graziano, and P. Tramonti
In a previous paper, we report a preliminary DSC study on bovine (BSA) and human (HSA) serum albumins. However, at accurate
HPLC analysis the commercial proteins show three peaks: Fraction V-I, probably globulins (as declared by the producers), Fraction
V-II (about 15–18% of the product) and Fraction V-III that represents pure BSA or HSA. A hypothesis is that the Fraction II
is a covalent dimer, or trimer or a mixture of both, generated during the scalf-life of the commercial product.
Denaturation enthalpies of the purified Fraction V-III and Fraction V-II of BSA, have been determined calorimetrically, at
changing thepH, and the results of both compared with those obtained on the untreated protein. Few calorimetric experiments have been also
carried on a BSA monomer derivative with sulphidril group protected. Computer program have been developed for the deconvolution
of exo- and endothermic effects and for the analysis of thermal denaturation profiles.
The interactions of lanthanide ions (Ln3+) with bovine serum albumin (BSA) under mimetic physiological conditions (310.15 K, pH 6.7, 0.1MNaCl) were studied by microcalorimetry.
For the first time, based on Two Sets of Independent Sites Model, molar enthalpies (ΔrHm1, ΔrHm2) and coordination number (n1, n2) of the two sets of binding sites with different affinity were obtained directly from the microcalorimetric results. It was
shown that the interactions are endothermic and entropy-driving processes. By combining with fluorescence spectroscopy, other
thermodynamic parameters (ΔrGm1, ΔrSm1) were determined for high-affinity specific sites.
Using the pulse radiolysis technique, the oxidation of the biological protein bovine serum albumin (BSA) by the species N
, OH and Br
has been studied in aqueous solution. The repair of the N
oxidation by ascorbic acid and the effect of denaturing the protein on this repair has also been studied. The oxidation of Br
seems to follow a different course from that of the other oxidizing agents suggesting the possibility of positive hole mobility in this protein. The repair by ascorbic acid is found more effective in the case of denatured protein. The rate constants for the reaction of Br
are lower, in general, in the case of the denatured protein as compared with the undenatured BSA both at pH 6.9 and pH 10.7, suggesting that the convoluted structure of the protein plays a part in the process.
Authors:X. Cao, X. Yang, J. Shi, Y. Liu, and C. Wang
The effect of glucose (0–15 mass%) on the kinetics of bovine serum albumin (BSA) denatured aggregation at high concentration
in aqueous solution has been studied by differential scanning calorimetry. The observed denatured aggregation process was
irreversible and could be characterized by a denaturation temperature (Tm), apparent activation energy (Ea), the approximate order of reaction, and pre-exponential factor (A). As the glucose concentration increased from 0 to 15 mass%, Tm increased, Ea also increased from 514.59409±6.61489 to 548.48611±7.81302 kJ mol−1, and A/s−1 increased from 1.24239E79 to 5.59975E83. The stabilization increased with an increasing concentration of glucose, which was
attributed to its ability to alter protein denatured aggregation kinetics.
The kinetic analysis was carried out using a composite procedure involving the iso-conversional method and the master plots
method. The iso-conversional method indicated that denatured aggregation of BSA in the presence and absence of glucose should
conform to single reaction model. The master plots method suggested that the simple order reaction model best describe the
process. This study shows the combination of iso-conversional method and the master plots method can be used to quantitatively
model the denatured aggregation mechanism of the BSA in the presence and absence of glucose.