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Incoming links: Hiroyuki Noji
By Hiroyuki Noji, Ryohei Yasuda, Masasuke Yoshida, and Kazuhiko Kinosita Jr.. Nature 386, 299–302; published 20 March 1997. DOI 10.1038/386299a0.
Cited passages: publisher abstract and author information. The abstract describes fluorescent-filament observation of isolated F1 rotation; it does not establish the complete membrane-coupled synthesis assay.
Single-molecule observation of F1 rotation 2026-10-18
In 1997, Hiroyuki Noji and colleagues attached a fluorescent actin filament to the central shaft of isolated . With ATP supplied, the marker made sustained rotations. This exposed rotation directly, but used ATP hydrolysis: there was no membrane motor producing ATP from a proton-motive force in this assay.[ref]
Direct observation of the rotation of F1-ATPase by Hiroyuki Noji and others. Noji, Yasuda, Yoshida and Kinosita Jr., Direct observation of the rotation of F1-ATPase, Nature 386 (1997), 299–302, accessible primary abstract
A subsequent primary experiment made the optical readout much faster. Purified Escherichia coli was immobilized on glass in a -deep flow cell, with a gold bead attached to . With ATP and magnesium supplied, laser illumination and dark-field microscopy recorded bead positions at or frames per second. The position trajectory resolved turns and intervening dwells. This apparatus follows a shaft-attached marker, rather than imaging the shaft's chemical atoms.[ref]
Temperature Dependence of Single Molecule Rotation of the Escherichia coli ATP Synthase F1 Sector Reveals the Importance of γ-β Subunit Interactions in the Catalytic Dwell by Mizuki Sekiya and others. Sekiya et al., 2009, Experimental Procedures: Direct Observation of gamma Subunit Rotation; Results, Figure 1
Controls addressed perturbation and chemical activity: comparison of – probes found similar rates for the two smallest sizes, supporting low drag; a separate coupled-enzyme assay followed ATP hydrolysis through NADH absorbance. But the rotational analysis excluded pauses longer than , so it characterizes continuously active intervals, not total output including long inhibited periods. It neither counts transported protons nor measures simultaneous single-molecule ATP synthesis.[ref]
Temperature Dependence of Single Molecule Rotation of the Escherichia coli ATP Synthase F1 Sector Reveals the Importance of γ-β Subunit Interactions in the Catalytic Dwell by Mizuki Sekiya and others. Sekiya et al., 2009, Experimental Procedures: Assay methods and data selection; Results: Direct Observation of Rotation Using a 60-nm Gold Bead
The experimental distinction is essential. Sustained directional marker motion tests a rotary mechanism. Demonstrating proton-driven synthesis additionally requires intact in a membrane with a controlled proton-motive force and a chemical ATP-production readout; dependence on that driving force and inhibition or respiratory uncoupling controls then test the proposed energy coupling. A rotation movie alone cannot establish the complete material and free energy ledger.