Structure characterization of membrane bound and surface adsorbed protein

Area of Science:

• Biophysics
• Surface Science
• Protein Chemistry

Background:

• Cytochrome c is a crucial protein involved in electron transport.
• Understanding protein-surface interactions is vital for biosensor and biomaterial development.
• Previous methods lacked resolution for detailed surface-bound protein structures.

Purpose of the Study:

• To investigate the structural topology of cytochrome c adsorbed on metal and lipid surfaces using X-ray standing waves.
• To determine the orientation and packing arrangement of cytochrome c upon surface binding.
• To assess the structural integrity of cytochrome c after surface adsorption and storage.

Main Methods:

• X-ray standing wave (XSW) analysis was employed.
• Experiments were conducted on cytochrome c bound to negatively charged model membranes and adsorbed at a metal surface.
• Surface-bound protein structure was analyzed using XSW reflectivity.

Main Results:

• Cytochrome c formed an ordered, hexagonally close-packed monolayer at the metal surface.
• Similar packing was observed on a self-assembled lipid film.
• The protein maintained its native globular structure after binding and extended storage.
• Data indicated a specific docking mechanism with the heme plane oriented perpendicular to the surface.

Conclusions:

• X-ray standing waves are a powerful tool for studying membrane- and surface-protein interactions.
• Cytochrome c maintains structural integrity and adopts a defined orientation upon surface binding.
• The findings provide insights into protein adsorption mechanisms relevant to various applications.