Determination of sedimentation coefficients for small peptides

Area of Science:

• Biophysical Chemistry
• Macromolecular Science
• Analytical Biochemistry

Background:

• Sedimentation velocity analysis is crucial for characterizing macromolecules.
• Obtaining accurate sedimentation coefficients can be challenging without distinct solvent and solution plateaus.
• The Lamm equations are fundamental for modeling sedimentation behavior.

Purpose of the Study:

• To develop and validate a direct fitting method for sedimentation velocity data using numerical solutions of the Lamm equations.
• To determine sedimentation and diffusion coefficients for small peptides under challenging experimental conditions.
• To assess the utility of the Lamm equations as data analysis tools.

Main Methods:

• Direct fitting of sedimentation velocity data to numerical solutions of the Lamm equations.
• Initialization of calculated evolution with the first experimental scan.
• Nonlinear regression analysis to determine sedimentation and diffusion coefficients.

Main Results:

• The method successfully determined sedimentation coefficients for small peptides (0.37, 0.45, and 0.52 S).
• Results showed good agreement with predictions from hydrodynamic theory.
• The approach is applicable to various experimental setups and macromolecule sizes.

Conclusions:

• Direct fitting of Lamm equation solutions provides a robust method for sedimentation coefficient determination.
• This technique is valuable for analyzing sedimentation data when traditional plateau methods fail.
• The method enhances the characterization of macromolecular shape, heterogeneity, and association states.