Open AccessThe Site of Force Generation in Muscle Contraction as Deduced from Fluorescence Polarization Studies
Author(s) -
T. Nihei,
Robert A. Mendelson,
Jean Botts
Publication year - 1974
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.71.2.274
Subject(s) - sarcomere , myosin , biophysics , muscle contraction , contraction (grammar) , fluorescence , actin , chemistry , muscle relaxation , fluorescence anisotropy , relaxation (psychology) , meromyosin , myosin head , anatomy , biochemistry , myocyte , biology , physics , myosin light chain kinase , membrane , optics , microbiology and biotechnology , neuroscience , endocrinology
The fluorescent dye,N (-iodoacetylamino)-l-naphthylanine-5-sulfonic acid, labeled exclusively the myosin cross-bridges in rabbit glycerinated psoas muscle fibers, without impairing their function. Fluorescence polarization was used to study cross-bridge orientation in rigor, relaxation, and contraction, as a function of sarcomere length. At a length where no overlap between thick and thin filaments occurs, rigor-inducing, relaxation-inducing, and contraction-inducing solutions all induced the relaxation attitude. At lengths where overlap does exist, the slowly-hydrolyzing ATP analog, “α,β-methylene ATP,” induced the relaxation attitude. The data were consistent with the A. F. Huxley-Simmons model of force generation. Combined with our earlier results, the data indicated that torque was generated at the actin-myosin interface.