Bovine serum albumin

About: Bovine serum albumin is a research topic. Over the lifetime, 19981 publications have been published within this topic receiving 571291 citations. The topic is also known as: BSA.

Kinetics of Thermal Denaturation and Aggregation of Bovine Serum Albumin.

Abstract: Thermal aggregation of bovine serum albumin (BSA) has been studied using dynamic light scattering, asymmetric flow field-flow fractionation and analytical ultracentrifugation. The studies were carried out at fixed temperatures (60°C, 65°C, 70°C and 80°C) in 0.1 M phosphate buffer, pH 7.0, at BSA concentration of 1 mg/ml. Thermal denaturation of the protein was studied by differential scanning calorimetry. Analysis of the experimental data shows that at 65°C the stage of protein unfolding and individual stages of protein aggregation are markedly separated in time. This circumstance allowed us to propose the following mechanism of thermal aggregation of BSA. Protein unfolding results in the formation of two forms of the non-native protein with different propensity to aggregation. One of the forms (highly reactive unfolded form, Uhr) is characterized by a high rate of aggregation. Aggregation of Uhr leads to the formation of primary aggregates with the hydrodynamic radius (Rh,1) of 10.3 nm. The second form (low reactive unfolded form, Ulr) participates in the aggregation process by its attachment to the primary aggregates produced by the Uhr form and possesses ability for self-aggregation with formation of stable small-sized aggregates (Ast). At complete exhaustion of Ulr, secondary aggregates with the hydrodynamic radius (Rh,2) of 12.8 nm are formed. At 60°C the rates of unfolding and aggregation are commensurate, at 70°C the rates of formation of the primary and secondary aggregates are commensurate, at 80°C the registration of the initial stages of aggregation is complicated by formation of large-sized aggregates.

Carrier-Mediated Transport of Thyroid Hormones through the Rat Blood-Brain Barrier: Primary Role of Albumin-Bound Hormone*

Abstract: The transport of [l25I]T3., and [l25I]T4 through the brain capillary wall, i.e. the blood-brain barrier, was studied in barbiturate-anesthetized rats using a tissue-sampling-carotid injection technique. The percent extraction of unidirectional influx of thyroid hormone during a single pass through the brain was measured relative to a highly diffusible [3H]water reference. The Km of T3 transport was 1.1 μM; T3 transport was inhibited by T4 (Ki = 2.6 μM), rT3;, (Ki = 5.4 μM), and D-T3 but not by 1000 μM concentrations of tyrosine, leucine, or potassium iodide. Bovine albumin also inhibited blood-brain barrier transport of T3). The fractional inhibition of T3 transport by albumin was a measure of the binding of T3 by albumin in vivo, i.e. in the presence of a competing binding system, the BBB T3 carrier. The apparent dissociation constant (Kd) of albumin binding of T3 at the brain capillary level (76 μM) was 16-fold greater than the K3 of albumin binding of T3 in vitro (4.7 μM), as determined by equilibrium ...

A selective oleic acid albumin agar medium for the cultivation of Mycobacterium bovis

Abstract: The modification of Middlebrook's 7H11 oleic acid albumin agar medium by the addition of fresh bovine serum and lysed sheep red cells to encourage growth of Mycobacterium bovis is described. The improved medium was made selective by the addition of antibiotics and a comparative trial of this medium and the guineapig test in the isolation of M. bovis from badger tissues is reported. A close agreement between the two tests was found; the guinea-pig test detected 95% of all isolations and culture detected 91%.

Beryllium Binding by Bovine Serum Albumin at Acid pH

Abstract: The binding of beryllium by bovine serum albumin was investigated, at three temperatures, in the pH region 5 and below', where beryllium salts are soluble and dialyzable. Reversible association was studied by the method of equilibrium dialysis in solutions containing nitrate ion at an ionic strength of 0.15. The amount of binding increased with increasing pH and temperature. The constancy of the intrinsic association constant (K = 36.2) and the variation of n, the number of binding sites, suggest that environmental conditions modfy the structure of the protein so that a varying number of a single class of binding sites become available for reaction. Considerations of the effect of pH and temperatare on beryllium ion hydrolysis and albumin structure support this interpretation. Esterified serum albumin exhibited no beryllium binding, which is evidence for the carboxyls as the reacting groups. The results of potentiometric titrations agreed with those obtained from equilibrium dialysis. Albumin denatured by dodecyl sulfate showed greatly increased beryllium binding, which was attributed to the electrostatic effect of the bound anion. The cooperative behavior of the beryllium binding was ascribed to the structural effects induced by dodecyl sulfate bound to albumin. Although the beryllium species in equilibrium with themore » protein is unknown, the data suggest that Be/sup 2+/ is one reacting species. (auth)« less