Low-frequency ultrasound absorption in aqueous solutions of hemoglobin, myoglobin, and bovine serum albumin: The role of structure and pH

Abstract

New measurements on ultrasound absorption of aqueous solutions of the three globular proteins, bovine hemoglobin, horse heart myoglobin, and bovine serum albumin, at 20 degrees C are reported for the frequency range below 1.2 MHz and, in the case of hemoglobin and bovine serum albumin, to a limited extent for the range 2-30 MHz. The effect of protein conformation has been investigated by use of a range of denaturants and by change of pH. A much more detailed description of protein interactions emerges from the low-frequency studies than was possible hitherto. Specific absorption processes for myoglobin and bovine serum albumin peak in the neighborhood of pH 4.2. The process for myoglobin has a relaxation frequency between 1 and 2.6 MHz, while for bovine serum albumin the frequency is as low as 70 kHz. Both processes can be related to conformational changes in the molecules. In the case of hemoglobin, an absorption process with a relaxation frequency of 600 kHz is found that can be attributed to the dissociation equilibrium of the quaternary structure of the molecule and can be considerably enhanced by denaturants or pH change from neutral to acid conditions. Measurements at frequencies down to 200 kHz have also permitted a more thorough investigation of proton-transfer reactions at carboxyl and amino groups in these proteins and of the effect of pH on these reactions.

Measurement of the Ultrasound Attenuation and Dispersion in Whole Human Blood and its Components From 0–70 MHz

“…The molecular level absorption mechanisms include viscosity and thermal conduction (the ''classical'' relaxation phenomena) along with additional structural and thermal relaxation processes (Bamber 2004). The cellular level absorption mechanisms include viscous relative motion and thermal conduction due to the inhomogeneous Carstensen et al (1953) Human RBC in plasma 0-85% -0.8-3 Carstensen and Schwan (1959a) Bovine RBC in plasma 40% 25 0.7-10 Carstensen and Schwan (1959a) Bovine RBC in saline 13-95% 25 0.7-10 Carstensen and Schwan (1959b) Human Hb solutions 4-30 g/dL 7-35 0.5-10 Edmonds (1962) Bovine Hb solutions 4-33 g/dL 5-25 32-232 Schneider et al (1969) Bovine Hb solutions 8-18 g/dL 8-25 0.5-1000 Edmonds et al (1970) Bovine Hb solutions 15 g/dL 25 10-130 Woodcock (1970) Human RBC in saline --6-10 White and Slutsky (1971) Bovine Hb solutions 15 g/dL 0 3-70 O 'Brien Jr. and Dunn (1972) Bovine Hb solutions -10 0.3-50 White and Slutsky (1972) Bovine Hb solutions 0.0023 M 0 5-50 Kikuchi et al (1972) Whole human blood 47% 37 2-10 Kremkau et al (1973) Fixed bovine RBC -25 5-90 Shung and Reid (1977) Whole human blood 8.7 g/dL 22 7-10 Hughes et al (1979) Canine RBC in plasma 0-53% 37 10 Narayana et al (1984) Whole human blood -22 4.8 Kremkau and Cowgill (1984) Hb solutions 8.5 g/dL 22 1-90 Kremkau and Cowgill (1985) Hb solutions 5 g/dL 21-22 1-90 Kremkau (1988) Hb solutions 9-21 g/dL 20-22 1-90 Yuan and Shung (1988) Porcine RBC in plasma 11-47% 23 3.5-12.5 Dai and Feng (1988) Bovine RBC in saline 17% -2-6 Barnes et al (1988) Bovine Hb solutions 2-15 g/dL 20 0.2-1.2 Lockwood et al (1991) Human RBC in saline 44% -30-60 Wang and Shung (1997) Porcine RBC in saline 5-45% room 5-30 Secomski et al (2001) Whole human blood 24-52% 37 16, 20 Maruvada et al (2002) Porcine RBC in saline 6-30% -30-90 Stride and Saffari (2004) Whole human blood -29 3-5 Hughes et al (2005) Whole porcine blood 40% 37 2-8 Dukhin et al (2006) Human RBC in plasma 9-95% -2-100 …”

Effect of Ultrasound on DNA Polymerase Reactions: Monitoring on a 27-MHz Quartz Crystal Microbalance

“…An ultrasound wave, a periodic pressure fluctuation, is also expected to control the enzyme characteristics as a dynamic perturbation. Linear polymers generally absorb a wide range of sound and ultrasound waves (10 3 to 10 6 Hz) through mechanical relaxations according to the molecular weight and relaxation mode. − Proteins, as biopolymers, also show ultrasound absorption in aqueous solution relating to conformational changes of biopolymers. , Therefore, a sound−ultrasound wave in the range of 10s to several 100s of kilohertz would perturb loop and domain motions of enzymes. , Also, these forced conformational motions of enzymes would affect the enzyme activity itself.…”