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Solvent viscosity effects on protein dynamics studied by ultrasonic absorption
A Almagor1, S Yedgar, B Gavish
1Biochemistry Department, Hebrew University, Hadassah Medical School, Jerusalem, Israel.
Biorheology
|January 1, 1990
Summary
Viscous cosolvents affect protein ultrasonic absorption. Small molecules correlate with viscosity, but large molecules and dextran do not, suggesting complex interactions beyond simple viscosity.
Area of Science:
- Biophysics
- Biochemistry
- Physical Chemistry
Background:
- Solvent viscosity influences biochemical reaction kinetics.
- Viscous cosolvents may modulate protein dynamic structure.
- Investigating protein-solvent interactions is crucial for understanding biological processes.
Purpose of the Study:
- To investigate the effect of viscous cosolvents of varying molecular sizes on bovine serum albumin (BSA) ultrasonic absorption.
- To examine the predicted modulating effect of cosolvents on protein "internal friction".
- To explore differences between microscopic and macroscopic solvent viscosity interpretations.
Main Methods:
- Measurement of apparent ultrasonic absorption of BSA in solution at 37°C.
- Use of viscous cosolvents with varying molecular sizes.
- Analysis of ultrasonic absorption (3-17 MHz) as a function of cosolvent concentration and viscosity.
Main Results:
- Ultrasonic absorption by BSA increased with cosolvent concentration.
- This increase correlated with solvent viscosity for small cosolvent molecules.
- No correlation was observed for macromolecular cosolvents or dextran solutions despite viscosity variations.
Conclusions:
- Protein ultrasonic absorption is influenced by cosolvent concentration and molecular size.
- The relationship between solvent viscosity and protein dynamics is complex and size-dependent.
- Macromolecular cosolvents may interact with proteins differently than small molecules, affecting energy dissipation mechanisms.