N-terminal acetylation does not alter α-synuclein's interfacial properties.

Area of Science:

• Biophysics
• Protein Chemistry
• Neuroscience

Background:

• Alpha-synuclein (αS) is a neuronal protein implicated in synucleinopathies.
• Native αS is N-terminally acetylated, influencing its structure and function.
• αS exhibits distinct conformations in solution versus membrane-bound states.

Purpose of the Study:

• To compare the interfacial behavior of N-terminal acetylated αS (Ac-αS) and non-acetylated αS (NH2-αS).
• To investigate the self-assembly and conformational changes of αS at the air-water interface.

Main Methods:

• Surface pressure-area isotherm measurements at the air-water interface.
• Compression-expansion cycles to study monolayer stability and hysteresis.
• Circular dichroism (CD) and linear dichroism (LD) spectroscopy of deposited films.

Main Results:

• Both Ac-αS and NH2-αS are highly surface-active, reaching ~30 mN/m surface pressure.
• Significant hysteresis in compression-expansion cycles indicates αS self-assembly and monolayer collapse.
• CD and LD analyses reveal predominantly α-helical structures and anisotropic deposition.

Conclusions:

• N-terminal acetylation does not abolish the surface activity of αS.
• Langmuir film formation and Blodgett deposition offer a method for creating oriented monolayers of surface-active proteins.
• Understanding αS interfacial properties is crucial for synucleinopathy research.