Biomechanics, One Molecule at a Time

Amit D Mehta,Matthias Rief,James A Spudich

doi:10.1074/jbc.274.21.14517

Abstract

Biomechanics, One Molecule at a Time

Highlights

Processive Motors A processive enzyme undergoes multiple productive catalytic cycles per diffusional encounter with its binding partner
If kinesin stepping proceeds with clocklike regularity, meaning a large number of processes are comparably rate-limiting for each mechanical step, all kinesin encounters with its track should proceed with the same time course
As Svoboda et al [9] calculate, if a single chemical transition limits the rate of each mechanical step, the variance rises with a slope of velocity times step size

Summary

Introduction

Processive Motors A processive enzyme undergoes multiple productive catalytic cycles per diffusional encounter with its binding partner. Schnitzer et al [10] performed like experiments under a broad range of ATP concentrations and showed ensemble variance under limited ATP was consistent with a single rate-limiting process, ATP binding, per mechanical advance. Wang et al [18] used a feedback scheme to increase effective trap strength while reducing light exposure; they measured stall forces of 21–27 pN, considerably above the 5–7 pN required to stall single kinesin motors.

Results

Conclusion