Modern analytical ultracentrifugation in protein science: look forward, not back.

The reasons for replacing the classical strictly two-component velocity and equilibrium analytical ultracentrifugation Svedberg equations by multicomponent equations, applicable in the study of biological macromolecular systems, are given.

Adair was right in his time.

The subunit molar mass of hemoglobin was established in the 19th century by chemical analysis, the tetramer structure by osmotic pressure determination in 1924 and by the newly developed analytical ultracentrifuge in 1926, which became a powerful tool for biological macromolecule molar mass determinations. The Svedberg equation was derived by eliminating the translational friction coefficient relating to sedimentation and diffusion in the ultracentrifuge in a strictly solute/solvent vanishing concentration two-component system analysis. A differential equation describing the radial equilibrium concentration distribution in the ultracentrifuge was also derived, both yielding the buoyant molar mass (1-nu2rho)M2 term.