Ultrasonic velocities, isentropic compressibilities and viscosities of bovine serum albumin in water and water containing organic solvents, sodium lauryl sulphate and tetrabutylammonium iodide at 310 K

Abstract

Ultrasonic velocities <i>(u), </i> densities (ρ) and viscosities (η) of bovine serum albumin (BSA)have been measured in the protein concentration range 0.0022 to 0.0430 g cm^-3 at 310 K in water and water containing 11.1 (v/v) % methanol (MeOH), acetonitrile (AN), N,N-dimethylformamide (DMF) and dimethylsulphoxide (DMSO). Such studies have also been made in water containing 0.042 mol dm^-3 sodium lauryl sulphate (SLS) and 0.033 mol dm^-3 tetrabutylammonium iodide (Bu₄NI). The isentropic compressibilities (<i>K</i>_s) of the protein have been estimated in all these systems. Both ultrasonic velocity and isentropic compressibility significantly vary with protein concentration indicating strong structural changes (conformational changes) of the protein in all these solvent systems. Viscosity results also indicate that BSA undergoes strong structural changes in the presence of SLS.