Electrokinetic detection of single-molecule phosphorylation

ABSTRACT Current single-molecule fluorescence experiments lack direct sensitivity to molecular phosphorylation state. We show that electrokinetic properties measured with an anti-Brownian trap resolve the number of phosphorylated sites on individual biomolecules and can monitor phosphorylation cycles with single kinase turn overs. As an application, we directly visualize the rate limiting step in the kinase catalytic cycle. Competing Interest Statement The authors have declared no competing interest. Copyright The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available for use under a CC0 license.