Ultrasonic Absorption in Aqueous Solutions of Globular Proteins

Abstract

The ultrasonic absorption and velocity were measured in aqueous solutions of bovine hemoglobin, a globular protein, which undergoes marked configurational change with pH, at 10°C over the frequency range 0.4 MHz to 50 MHz and over the pH range 1.5–13.5. As the pH is varied outside the range 5<pH<9, the excess absorption increases sharply, this effect being more pronounced at lower frequencies. Similarities in results between bovine hemoglobin and another globular protein, bovine serum albumin [L. W. Kessler and F. Dunn, J. Phys. Chem., to be published], are discussed, and a possible cause is proposed that accounts for these similarities. [This work is supported by the Institute of General Medical Sciences, National Institute of Health.]