# Nucleotide Exchange Mechanism Involving Angle-Dependent Rate Constants Extracted from F1-ATPase Single-Molecule Rotation Trajectories

## TL;DR

This paper studies how F1-ATPase rotates by analyzing nucleotide exchange rates, revealing a coordinated mechanism of ATP binding and ADP release.

## Contribution

A new theory of reaction kinetics is developed to extract angle-dependent rate constants from single-molecule rotation data.

## Key findings

- Angle-dependent rate constants for nucleotide binding and release were extracted from F1-ATPase rotation data.
- The concerted mechanism is driven by correlated conformational changes in the F1-ATPase ring.
- The kinetic signature is a unified function independent of ATP concentration.

## Abstract

Evidence has been mounting that in the rotational cycle
of F1-ATPase
there is a concerted ATP binding and ADP release that yields a million-fold
acceleration in the rate of the product ADP release. We developed
a theory of reaction kinetics to investigate the relationship between
the concerted nucleotide exchange and previous single-molecule forced
rotation data from

AdachiK.,

Nat. Commun.
2012, 3, 1022
22929779
10.1038/ncomms2026PMC3449090. We extracted from these data angle-dependent rate constants
for nucleotide binding and release. The rate constants were then used
in a unified kinetic scheme, also consistent with other single-molecule
and ensemble experiments, to obtain analytical equations for nucleotide
occupancy change events from nano- to millimolar ATP concentrations.
A theory-experiment comparison revealed novel evidence about the concerted
mechanism: it is determined by correlated conformational changes in
the F1-ATPase ring, and its kinetic signature is a unified angle-dependent
function of the nucleotide binding and release rate constants, which
is independent of ATP concentration.