Evidence for pre-and post-power stroke of cross-bridges of contracting skeletal myofibrils

K. Midde, R. Luchowski, Hriday Das, J. Fedorick, V. Dumka, Ignacy Gryczynski, Zygmunt Gryczynski, Julian Borejdo

Research output: Contribution to journalArticle

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Abstract

We examined the orientational fluctuations of a small number of myosin molecules (approximately three) in working skeletal muscle myofibrils. Myosin light chain 1 (LC1) was labeled with a fluorescent dye and exchanged with the native LC1 of skeletal muscle myofibrils cross-linked with 1-ethyl-3- [3(dimethylamino) propyl] carbodiimide to prevent shortening. We observed a small volume within the A-band (∼10T-15 L) by confocal microscopy, and measured cyclic fluctuations in the orientation of the myosin neck (containing LC1) by recording the parallel and perpendicular components of fluorescent light emitted by the fluorescently labeled myosin LC1. Histograms of orientational fluctuations from fluorescent molecules in rigor were represented by a single Gaussian distribution. In contrast, histograms from contracting muscles were best fit by at least two Gaussians. These results provide direct evidence that cross-bridges in working skeletal muscle assume two distinct conformations, presumably corresponding to the pre-and post-power-stroke states.

Original languageEnglish
Pages (from-to)1024-1033
Number of pages10
JournalBiophysical Journal
Volume100
Issue number4
DOIs
StatePublished - 16 Feb 2011

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Myofibrils
Myosin Light Chains
Skeletal Muscle
Stroke
Myosins
Light
Carbodiimides
Normal Distribution
Fluorescent Dyes
Confocal Microscopy
Neck
Muscles

Cite this

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abstract = "We examined the orientational fluctuations of a small number of myosin molecules (approximately three) in working skeletal muscle myofibrils. Myosin light chain 1 (LC1) was labeled with a fluorescent dye and exchanged with the native LC1 of skeletal muscle myofibrils cross-linked with 1-ethyl-3- [3(dimethylamino) propyl] carbodiimide to prevent shortening. We observed a small volume within the A-band (∼10T-15 L) by confocal microscopy, and measured cyclic fluctuations in the orientation of the myosin neck (containing LC1) by recording the parallel and perpendicular components of fluorescent light emitted by the fluorescently labeled myosin LC1. Histograms of orientational fluctuations from fluorescent molecules in rigor were represented by a single Gaussian distribution. In contrast, histograms from contracting muscles were best fit by at least two Gaussians. These results provide direct evidence that cross-bridges in working skeletal muscle assume two distinct conformations, presumably corresponding to the pre-and post-power-stroke states.",
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Evidence for pre-and post-power stroke of cross-bridges of contracting skeletal myofibrils. / Midde, K.; Luchowski, R.; Das, Hriday; Fedorick, J.; Dumka, V.; Gryczynski, Ignacy; Gryczynski, Zygmunt; Borejdo, Julian.

In: Biophysical Journal, Vol. 100, No. 4, 16.02.2011, p. 1024-1033.

Research output: Contribution to journalArticle

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AU - Gryczynski, Ignacy

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AU - Borejdo, Julian

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