Measurements of the half-sarcomere stiffness during activation of skinned fibers from rabbit psoas (sarcomere length 2.5 um, temperature 12°C) indicate that addition of 0.1 mM orthovanadate (Vi) to the solution produces a drop to ~1/2 in number of force-generating myosin motors, proportional to the drop in steady isometric force (T0), an effect similar to that produced by the addition of 10 mM phosphate (Pi). However, in contrast to Pi, Vi does not change the rate of isometric force development. The depression of T0 in a series of activations in presence of Vi is consistent with an apparent second-order rate constant of ~1 *10^3 M-1s-1. The rate constant of T0 recovery in a series of activations after removal of Vi is 3.5 * 10^-2 s-1. These results, together with the finding in the literature that the ATPase rate is reduced by Vi in proportion to isometric force, are reproduced with a kinetic model of the acto-myosin cross-bridge cycle where binding of Vi to the force-generating actomyosin- ADP state induces detachment from actin to form a stable myosin-ADP-Vi complex that is not able to complete the hydrolysis cycle and reenters the cycle only via reattachment to actin upon activation in Vi-free solution.

Orthovanadate and orthophosphate inhibit muscle force via two different pathways of the myosin ATPase cycle / M. Caremani; S. Lehman; V. Lombardi; M. Linari. - In: BIOPHYSICAL JOURNAL. - ISSN 0006-3495. - STAMPA. - 100:(2011), pp. 665-674. [10.1016/j.bpj.2010.12.3723]

Orthovanadate and orthophosphate inhibit muscle force via two different pathways of the myosin ATPase cycle

CAREMANI, MARCO;LOMBARDI, VINCENZO;LINARI, MARCO
2011

Abstract

Measurements of the half-sarcomere stiffness during activation of skinned fibers from rabbit psoas (sarcomere length 2.5 um, temperature 12°C) indicate that addition of 0.1 mM orthovanadate (Vi) to the solution produces a drop to ~1/2 in number of force-generating myosin motors, proportional to the drop in steady isometric force (T0), an effect similar to that produced by the addition of 10 mM phosphate (Pi). However, in contrast to Pi, Vi does not change the rate of isometric force development. The depression of T0 in a series of activations in presence of Vi is consistent with an apparent second-order rate constant of ~1 *10^3 M-1s-1. The rate constant of T0 recovery in a series of activations after removal of Vi is 3.5 * 10^-2 s-1. These results, together with the finding in the literature that the ATPase rate is reduced by Vi in proportion to isometric force, are reproduced with a kinetic model of the acto-myosin cross-bridge cycle where binding of Vi to the force-generating actomyosin- ADP state induces detachment from actin to form a stable myosin-ADP-Vi complex that is not able to complete the hydrolysis cycle and reenters the cycle only via reattachment to actin upon activation in Vi-free solution.
2011
100
665
674
M. Caremani; S. Lehman; V. Lombardi; M. Linari
File in questo prodotto:
File Dimensione Formato  
Caremani et al 2011.pdf

accesso aperto

Tipologia: Versione finale referata (Postprint, Accepted manuscript)
Licenza: Open Access
Dimensione 307.25 kB
Formato Adobe PDF
307.25 kB Adobe PDF
Supplementary material.pdf

accesso aperto

Tipologia: Versione finale referata (Postprint, Accepted manuscript)
Licenza: Open Access
Dimensione 33.21 kB
Formato Adobe PDF
33.21 kB Adobe PDF

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/2158/564696
Citazioni
  • ???jsp.display-item.citation.pmc??? 3
  • Scopus 5
  • ???jsp.display-item.citation.isi??? 5
social impact