Sedimentation of rapidly interacting multicomponent systems

TL;DR

This paper develops a theoretical framework for sedimentation velocity ultracentrifugation to analyze rapidly interacting multi-protein systems, enabling better understanding of their complex formation and interactions.

Contribution

It introduces a new theory for multi-component sedimentation of fast-interacting systems, extending the analytical capabilities of SV ultracentrifugation.

Findings

Reveals physical principles governing rapid multi-component sedimentation.

Provides a quantitative framework for analyzing transient complexes.

Extends the dynamic range of sedimentation velocity techniques.

Abstract

The biophysical analysis of dynamically formed multi-protein complexes in solution presents a formidable technical challenge. Sedimentation velocity (SV) analytical ultracentrifugation achieves strongly size-dependent hydrodynamic resolution of different size species, and can be combined with multi-component detection by exploiting different spectral properties or temporally modulated signals from photoswitchable proteins. Coexisting complexes arising from self- or hetero-associations that can be distinguished in SV allow measurement of their stoichiometry, affinity, and cooperativity. However, assemblies that are short-lived on the time-scale of sedimentation (t1/2 < 100 sec) will exhibit an as of yet unexplored pattern of sedimentation boundaries governed by coupled co-migration of the entire system. Here, we present a theory for multi-component sedimentation of rapidly interacting systems, which reveals simple underlying physical principles, offers a quantitative framework for analysis, thereby extending the dynamic range of SV for studying multi-component interactions