Probing protein-surfactant interaction by steady state and time-resolved fluorescence spectroscopy

Area of Science:

• Biophysical Chemistry
• Protein Dynamics
• Fluorescence Spectroscopy

Background:

• Bovine serum albumin (BSA) is a crucial protein with a complex microenvironment.
• Understanding protein-ligand interactions requires probing the local environment.
• Fluorescence probes like coumarin 153 (C-153) and 8-anilino-1-naphthalenesulfonic acid (ANS) are used to study microenvironments.

Purpose of the Study:

• To investigate the microenvironment of bovine serum albumin (BSA) using fluorescence probes.
• To compare solvation dynamics and probe behavior in native BSA, BSA-surfactant complexes, and pure micelles.
• To elucidate the structural implications of BSA-surfactant interactions on protein dynamics.

Main Methods:

• Utilized fluorescence spectroscopy with coumarin 153 (C-153) and 8-anilino-1-naphthalenesulfonic acid (ANS) as probes.
• Studied probe solvation dynamics and rotational motion in different environments.
• Investigated BSA in its native state, in 1% BSA solution, and in BSA-surfactant (SDS) complexes.

Main Results:

• The microenvironment within 1% BSA is significantly more hydrophobic than in pure micelles or protein-surfactant complexes.
• C-153 probe showed no solvation in native BSA, suggesting localization in a hydrophobic pocket.
• ANS probe detected slow dynamics on the BSA surface.
• BSA-SDS complexes exhibited distinct solvation dynamics and hindered rotational motion compared to pure micelles, possibly due to a 'necklace and bead' structure.

Conclusions:

• The hydrophobic nature of BSA's microenvironment influences probe behavior and solvation dynamics.
• Protein-surfactant complex formation alters the protein's local environment and dynamics.
• The findings provide insights into the structural organization and dynamic properties of BSA and its complexes.