The molecular mechanism of muscle contraction was investigated in intact muscle fibres by X-ray diffraction. Changes in the intensities of the axial X-ray reflections produced by imposing rapid changes in fibre length establish the average conformation of the myosin heads during active isometric contraction, and show that the heads tilt during the elastic response to a change in fibre length and during the elementary force generating process: the working stroke. X-ray interference between the two arrays of myosin heads in each filament allows the axial motions of the heads following a sudden drop in force from the isometric level to be measured in situ with unprecedented precision. At low load, the average working stroke is 12 nm, which is consistent with crystallographic studies. The working stroke is smaller and slower at a higher load. The compliance of the actin and myosin filaments was also determined from the change in the axial spacings of the X-ray reflections following a force step, and shown to be responsible for most of the sarcomere compliance. The mechanical properties of the sarcomere depend on both the motor actions of the myosin heads and the compliance of the myosin and actin filaments.

X-ray diffraction studies of the contractile mechanism in single muscle fibres / V. Lombardi; G. Piazzesi; M. Reconditi; M. Linari; L. Lucii; A. Stewart; Y.-B. Sun; P. Boesecke; T. Narayanan; T. Irving; M. Irving. - In: PHILOSOPHICAL TRANSACTIONS - ROYAL SOCIETY. BIOLOGICAL SCIENCES. - ISSN 0962-8436. - STAMPA. - 359:(2004), pp. 1883-1893. [10.1098/rstb.2004.1557]

X-ray diffraction studies of the contractile mechanism in single muscle fibres

LOMBARDI, VINCENZO;PIAZZESI, GABRIELLA;RECONDITI, MASSIMO;LINARI, MARCO;
2004

Abstract

The molecular mechanism of muscle contraction was investigated in intact muscle fibres by X-ray diffraction. Changes in the intensities of the axial X-ray reflections produced by imposing rapid changes in fibre length establish the average conformation of the myosin heads during active isometric contraction, and show that the heads tilt during the elastic response to a change in fibre length and during the elementary force generating process: the working stroke. X-ray interference between the two arrays of myosin heads in each filament allows the axial motions of the heads following a sudden drop in force from the isometric level to be measured in situ with unprecedented precision. At low load, the average working stroke is 12 nm, which is consistent with crystallographic studies. The working stroke is smaller and slower at a higher load. The compliance of the actin and myosin filaments was also determined from the change in the axial spacings of the X-ray reflections following a force step, and shown to be responsible for most of the sarcomere compliance. The mechanical properties of the sarcomere depend on both the motor actions of the myosin heads and the compliance of the myosin and actin filaments.
2004
359
1883
1893
V. Lombardi; G. Piazzesi; M. Reconditi; M. Linari; L. Lucii; A. Stewart; Y.-B. Sun; P. Boesecke; T. Narayanan; T. Irving; M. Irving
File in questo prodotto:
File Dimensione Formato  
Phylosophical Trans 2004.pdf

Accesso chiuso

Tipologia: Versione finale referata (Postprint, Accepted manuscript)
Licenza: DRM non definito
Dimensione 640.72 kB
Formato Adobe PDF
640.72 kB Adobe PDF   Richiedi una copia

I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/611918
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 28
  • ???jsp.display-item.citation.isi??? 25
social impact