A novel electron paramagnetic resonance spin label and its application to study the cross-bridge cycle

D. Raucher, E. A. Fajer, C. Sar, K. Hideg, Y. Zhao, M. Kawai, P. G. Fajer, B. Brenner, I. Rayment, K. Holmes

Research output: Contribution to journalArticle

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Abstract

We have used a novel α-iodoketone spin-label(IKSL) to study myosin head orientation and cross-bridge dynamics in the putative pre-powerstroke state. Possible perturbation of the cross-bridge cycle by the label was assayed by the sinusoidal analysis method (Kawai and Brandt, 1980; Kawai and Zhao, 1993), which determines the rate constants of the elementary steps in the cycle. A comparison of the rates obtained from unlabeled and IKSL fibers revealed small (10-20%) changes in the ATP hydrolysis rate and in the rate constants of the elementary steps. The labeling induced small changes (2+ and ATP. In this state, force development is inhibited, but a large proportion (40%) of the cross-bridges are still attached to the thin filament. We have used conventional electron paramagnetic resonance to measure orientation, and have found that the pre- powerstroke heads are as disordered as in relaxation. Their mobility, as determined by saturation transfer electron paramagnetic resonance, was significantly restricted. Assuming that stiffness is proportional to the fraction of strongly attached heads, the rotational correlation time of the bound heads is estimated to be τ(r) = ~150-400 μs.

Original languageEnglish
JournalBiophysical Journal
Volume68
Issue number4 SUPPL.
Publication statusPublished - 1995

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Spin Labels
Electron Spin Resonance Spectroscopy
Head
Adenosine Triphosphate
Myosins
Hydrolysis

ASJC Scopus subject areas

  • Biophysics

Cite this

Raucher, D., Fajer, E. A., Sar, C., Hideg, K., Zhao, Y., Kawai, M., ... Holmes, K. (1995). A novel electron paramagnetic resonance spin label and its application to study the cross-bridge cycle. Biophysical Journal, 68(4 SUPPL.).

A novel electron paramagnetic resonance spin label and its application to study the cross-bridge cycle. / Raucher, D.; Fajer, E. A.; Sar, C.; Hideg, K.; Zhao, Y.; Kawai, M.; Fajer, P. G.; Brenner, B.; Rayment, I.; Holmes, K.

In: Biophysical Journal, Vol. 68, No. 4 SUPPL., 1995.

Research output: Contribution to journalArticle

Raucher, D, Fajer, EA, Sar, C, Hideg, K, Zhao, Y, Kawai, M, Fajer, PG, Brenner, B, Rayment, I & Holmes, K 1995, 'A novel electron paramagnetic resonance spin label and its application to study the cross-bridge cycle', Biophysical Journal, vol. 68, no. 4 SUPPL..
Raucher, D. ; Fajer, E. A. ; Sar, C. ; Hideg, K. ; Zhao, Y. ; Kawai, M. ; Fajer, P. G. ; Brenner, B. ; Rayment, I. ; Holmes, K. / A novel electron paramagnetic resonance spin label and its application to study the cross-bridge cycle. In: Biophysical Journal. 1995 ; Vol. 68, No. 4 SUPPL.
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AU - Sar, C.

AU - Hideg, K.

AU - Zhao, Y.

AU - Kawai, M.

AU - Fajer, P. G.

AU - Brenner, B.

AU - Rayment, I.

AU - Holmes, K.

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