Quantitative mass imaging of single biological macromolecules

TLDR

Light‑scattering measurements enable accurate mass determination of individual proteins and complexes down to 20 kDa, allowing observation of their weight and interactions. The authors recorded unlabeled protein complexes in real time and analyzed the movies to extract single‑molecule biophysical parameters. They quantified in‑vitro fibril and aggregate growth kinetics and measured association constants for a complex protein‑glycoprotein assembly. Young et al., Science, this issue p.

Abstract

Watching proteins' weight Careful measurements of light scattering can provide information on individual macromolecules and complexes. Young et al. used a light-scattering approach for accurate mass determination of proteins as small as 20 kDa (see the Perspective by Lee and Klenerman). Movies of protein complex association and dissociation were analyzed to extract biophysical parameters from single molecules and assemblies without labeling. Using this approach, the authors determined in vitro kinetics of fibril and aggregate growth and association constants for a complex protein-glycoprotein assembly. Science , this issue p. 423 ; see also p. 378