[Study of temperature-dependent conformational changes in serum albumin using an adsorbed dye]

4-N (p-sulfoaniline),5-methoxy,1,2-benzoquinon (1) is bound by hydrophobic regions of the native molecule of bovine serum albumin (BSA). In the temperature interval 0--65 degrees C the interaction characteristics such as energy, entropy and the average number of the binding sites on a BSA molecule were determined. Under experimental conditions BSA is found in at least in two equilibrium conformational states distinguished by quantity of hydrophobic regions capable of binding with 1. Below 17 degrees C no conformational changes of BSA was observed. With the increase of temperature from 17 to 47 degrees C the equilibrium is driven in the direction of protein form with the hydrophobic binding sites which are more available for the solvent. Heating above 47 degrees C produces "predenaturation" structural changes in the BSA molecule. Hydrophobic regions of the BSA have different thermal stability.