The hydrodynamic motion of Nanodiscs

• Published in: Chemistry and physics of lipids 2019-05, Vol.220, p.28-35
• Main Authors: Camp, Tyler, McLean, Mark, Kato, Mallory, Cheruzel, Lionel, Sligar, Stephen
• Format: Article
• Language: English
• Subjects: chemical bonding; equations; Fluorescence; Fluorometry; Hydrodynamics; lipid bilayers; Lipid Bilayers - chemistry; membrane proteins; Membrane Proteins - chemistry; monitoring; Nanodiscs; Nanostructures - chemistry; Rotational motion; ruthenium; scaffolding proteins
• ISSN: 0009-3084; 1873-2941
• DOI: 10.1016/j.chemphyslip.2019.02.008

•Rotational correlation times of nanodiscs were accurately measured using fluorescence depolarization.•Nanodiscs of increasing diameters display longer overall rotational correlation times.•The long-lifetime dye attached to Nanodiscs allows sensitive, label-free detection of protein binding. We present a fluorescence-based methodology for monitoring the rotational dynamics of Nanodiscs. Nanodiscs are nano-scale lipid bilayers surrounded by a helical membrane scaffold protein (MSP) that have found considerable use in studying the interactions between membrane proteins and their lipid bilayer environment. Using a long-lifetime Ruthenium label covalently attached to the Nanodiscs, we find that Nanodiscs of increasing diameter, made by varying the number of helical repeats in the MSP, display increasing rotational correlation times. We also model our system using both analytical equations that describe rotating spheroids and numerical calculations performed on atomic models of Nanodiscs. Using these methods, we observe a linear relationship between the experimentally determined rotational correlation times and those calculated from both analytical equations and numerical solutions. This work sets the stage for accurate, label-free quantification of protein-lipid interactions at the membrane surface.