How to Measure Load-Dependent Kinetics of Individual Motor Molecules Without a Force-Clamp

Jongmin Sung, Kim Mortensen, James A. Spudich, Henrik Flyvbjerg

    Research output: Contribution to conferenceConference abstract for conferenceResearchpeer-review


    Molecular motors are responsible for numerous cellular processes from cargo transport to heart contraction. Their interactions with other cellular components are often transient and exhibit kinetics that depend on load. Here, we measure such interactions using a new method, Harmonic Force Spectroscopy. In this method, harmonic oscillation of the sample stage of a laser trap immediately, automatically and randomly applies sinusoidally varying loads to a single motor molecule interacting with a single track along which it moves. The experimental protocol and the data analysis are simple, fast and efficient. The protocol accumulates statistics fast enough to deliver single-molecule results from single-molecule experiments. We demonstrate the method's performance by measuring the force-dependent kinetics of individual human beta-cardiac myosin molecules interacting with an actin filament at physiological ATP concentration. We show that a molecule's ADP release rate depends exponentially on the applied load. This points to Kramer's Brownian diffusion model of chemical reactions as explanation why muscle contracts with a velocity inversely proportional to external load.
    Original languageEnglish
    Publication date2017
    Number of pages1
    Publication statusPublished - 2017
    Event30th Marian Smoluchowski Symposium on Statistical Physics - Krakow, Poland
    Duration: 3 Sep 20178 Sep 2017


    Conference30th Marian Smoluchowski Symposium on Statistical Physics

    Fingerprint Dive into the research topics of 'How to Measure Load-Dependent Kinetics of Individual Motor Molecules Without a Force-Clamp'. Together they form a unique fingerprint.

    Cite this