A study of Folch-Pi apoprotein. II. Relation between polymerization state and conformation

Area of Science:

• Biochemistry
• Protein Chemistry
• Spectroscopy

Background:

• Folch-Pi apoprotein is a key component of myelin.
• Understanding its conformational changes is crucial for myelin structure and function.

Purpose of the Study:

• To compare the conformation of Folch-Pi apoprotein in organic and aqueous environments.
• To investigate the molecular basis of its aggregation in aqueous solutions.

Main Methods:

• Electron spin resonance (ESR) spectroscopy
• Infrared spectroscopy
• Circular dichroism (CD) spectroscopy
• Electrophoresis
• Ultracentrifugation

Main Results:

• The protein exists as a monomer in organic solvents.
• In aqueous solutions, Folch-Pi apoprotein forms a polydisperse, associating system.
• Hydrophobic interactions drive this polymerization, without significant beta-structure formation.
• ESR spectra indicate heterogeneous motional environments in the aggregated protein.

Conclusions:

• Folch-Pi apoprotein undergoes significant conformational changes upon transfer from organic to aqueous solutions.
• Hydrophobic interactions are critical for its aqueous aggregation, suggesting specific association domains.
• The findings provide insights into the self-assembly properties of myelin proteins.