Adair was right in his time

Area of Science:

• Biophysical Chemistry
• Macromolecular Science
• Analytical Chemistry

Background:

• Historical methods for determining hemoglobin molar mass and structure.
• Development of the analytical ultracentrifuge and the Svedberg equation for macromolecule analysis.
• Recognition of limitations in two-component system analysis for biological macromolecules.

Purpose of the Study:

• To re-evaluate the thermodynamic principles underlying analytical ultracentrifugation.
• To introduce a multicomponent system approach for accurate molar mass determination.
• To demonstrate the advantages of the thermodynamic multicomponent approach over classical methods.

Main Methods:

• Derivation of thermodynamic equations for multicomponent systems in analytical ultracentrifugation.
• Determination of density increment at constant chemical potentials.
• Complementary use of light, X-ray, and neutron scattering experiments.

Main Results:

• Redefinition of buoyant molar mass terms for multicomponent systems.
• Accurate determination of molar mass (g/mol) using the density increment.
• High-precision studies of macromolecular interactions and solute-solvent interactions.
• Demonstration of the correctness and utility of the multicomponent approach.

Conclusions:

• The classical Svedberg approach, while historically significant, is limited in its applicability.
• The thermodynamic multicomponent system approach provides accurate molar mass and interaction data.
• Current analytical ultracentrifugation practices often overlook the powerful multicomponent solution technology.