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Large solutes induce structural perturbations in proteins and membranes.
Z E Sauna1, C N Madhavarao, V Sitaramam
1Department of Biotechnology, University of Pune, 411 007, Pune, India.
International Journal of Biological Macromolecules
|June 29, 2001
Summary
Solvents perturb biopolymers like proteins and DMPC vesicles by creating internal defects or voids. This structural change was observed using fluorescent probes, impacting their stability and dynamics.
Area of Science:
- Biophysics
- Biochemistry
- Materials Science
Background:
- Biopolymers such as proteins and lipid membranes possess hydrophobic interiors.
- Understanding structural dynamics is crucial for their function and stability.
- Solute-induced changes can reveal underlying structural properties.
Purpose of the Study:
- To investigate structural perturbations in biopolymers (proteins and DMPC vesicles) induced by varying solute concentrations.
- To characterize the nature of these structural changes using fluorescence spectroscopy.
Main Methods:
- Utilized 1,6-diphenyl-1,3,5-hexatriene (DPH) as a fluorescent probe.
- Measured steady-state and time-resolved fluorescence of DPH and intrinsic tryptophan (in BSA).
- Assessed potassium iodide quenching in proteins and terbium leakage in DMPC vesicles.
Main Results:
- Solutes decreased steady-state anisotropy and rotational correlation time of DPH in both proteins and vesicles.
- Observed enhanced accessibility of potassium iodide to tryptophan in bovine serum albumin (BSA) and ovalbumin.
- Detected increased terbium leakage from DMPC vesicles.
Conclusions:
- Solute-induced changes in fluorescence anisotropy and correlation times indicate structural perturbations.
- These perturbations are consistent with the formation of defects or voids within the biopolymer structures.
- The findings provide insights into the dynamic structural rearrangements of proteins and lipid membranes under varying environmental conditions.