Mechanochemical coupling in spin-labeled, active, isometric muscle

Josh E. Baker, Leslie E.W. LaConte, Ingrid Brust-Mascher, David D Thomas

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

Observed effects of inorganic phosphate (P(i)) on active isometric muscle may provide the answer to one of the fundamental questions in muscle biophysics: how are the free energies of the chemical species in the myosin- catalyzed ATP hydrolysis (ATPase) reaction coupled to muscle force? Pate and Cooke (1989. Pflugers Arch. 414:73-81) showed that active, isometric muscle force varies logarithmically with [P(i)]. Here, by simultaneously measuring electron paramagnetic resonance and the force of spin-labeled muscle fibers, we show that, in active, isometric muscle, the fraction of myosin heads in any given biochemical state is independent of both [P(i)] and force. These direct observations of mechanochemical coupling in muscle are immediately described by a muscle equation of state containing muscle force as a state variable. These results challenge the conventional assumption mechanochemical coupling is localized to individual myosin heads in muscle.

Original languageEnglish (US)
Pages (from-to)2657-2664
Number of pages8
JournalBiophysical journal
Volume77
Issue number5
DOIs
StatePublished - Nov 1999

Bibliographical note

Funding Information:
This work was supported by grants from the Muscular Dystrophy Association, the National Institutes of Health (AR32961), the Minnesota Supercomputer Institute, and the National Science Foundation.

Fingerprint Dive into the research topics of 'Mechanochemical coupling in spin-labeled, active, isometric muscle'. Together they form a unique fingerprint.

Cite this