Microsecond rotational motion of spin-labeled myosin heads during isometric muscle contraction. Saturation transfer electron paramagnetic resonance

Barnett, Vincent A.; Thomas, David D.

doi:10.1016/s0006-3495(89)82698-0

Cited by 50 publications

(36 citation statements)

References 27 publications

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“…However, other in vitro studies reported an angle close to that in rigor (Zot et al, 1990). The EPR studies that showed rotational motion of heads during contraction (Cooke et al, 1982;Barnett & Thomas, 1989;Fajer et al, 1990) are also consistent with our results.…”

Section: Angles Of the Crossbridgessupporting

confidence: 92%

“…X-ray diffraction (Huxley & Brown, 1967;Yagi et al, 1981;Huxley et al, 1982) and EPR studies (Cooke et al, 1982;Barnett & Thomas, 1989;Fajer et al, 1990) have suggested that the averaged structure of contracting muscle is different from that of rigor or relaxed muscle. The results of X-ray diffraction were interpreted to mean that during contraction the helical arrangement of myosin heads along thick filaments is disordered but the --, 14.3 nm subunit repeat is maintained.…”

confidence: 99%

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Structural change of crossbridges of rabbit skeletal muscle during isometric contraction

Hirose

Wakabayashi

1993

J Muscle Res Cell Motil

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Structural changes of crossbridges during isometric contraction have been studied by electron microscopy. Chemically skinned rabbit fibres were rapidly frozen either in activating solution or in ATP-free (rigor) solution, freeze-substituted and embedded. Longitudinal sections of muscle fibres show that the number of crossbridges in active fibres (isometric contraction) is approximately the same as in rigor fibres. Crossbridges of the active and rigor states differ in their shapes, angles and manner of arrangement on the thin filaments. In rigor many crossbridges are wide near the thin filaments and narrow near the thick filament shafts; in active fibres they have more uniform width along their length. The angle of the crossbridges in active fibres is somewhat variable. The average angle is approximately 90 degrees to the filament axis. The crossbridges are arranged on the thin filament retaining the 14.3 nm thick filament periodicity. The crossbridges in rigor are tilted and their arrangement near the thin filament reveals the 36 nm actin periodicity. The variability in the shapes of the crossbridges in active fibres is still higher when we look at them in cross-sections of muscle fibres. The crossbridge shapes in the cross-sections were classified and the relative frequency of different shapes was determined. The shapes that are commonly observed in active fibres are similar in that the majority of the mass of the crossbridges is farther away from the thin filament than the crossbridges in rigor fibres.

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Section: Angles Of the Crossbridgessupporting

confidence: 92%

confidence: 99%

Structural change of crossbridges of rabbit skeletal muscle during isometric contraction

Hirose

Wakabayashi

1993

J Muscle Res Cell Motil

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“…To directly test this hypothesis, the high resolution of electron paramagnetic resonance spectroscopy in combination with the specificity of site-specific spin labeling was used to investigate age-related alterations in the distribution of myosin structural states during muscle contraction. 11,12 Muscle fibers from young and aged rats were used in those studies. Specific force in fibers from older animals was 27% lower relative to fibers from the younger animals.…”

Section: Aging and Altered Protein Metabolismmentioning

confidence: 99%

Skeletal Muscle Adaptations with Age, Inactivity, and Therapeutic Exercise

Thompson¹

2002

J Orthop Sports Phys Ther

104

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One of the remarkable features of skeletal muscle is its adaptability. Skeletal muscle adaptations are characterized by modifications of morphological, biochemical, and molecular variables that alter the functional attributes of specific skeletal muscle fiber types. Skeletal muscle adaptation is diverse and the magnitude of change is dependent on many factors, such as activity pattern, age, and muscle fiber type composition. The adaptation of skeletal muscle in the adult population is well described. In contrast, the adaptation of skeletal muscle in the older population is less documented, especially in the area of inactivity-induced alterations. Age-related changes in skeletal muscle may play a significant role in the magnitude of change with inactivity and influence the rehabilitation process for the older adult.A consistent feature of age and inactivity is limb muscle atrophy and the loss of peak force and power. Differences exist in the rate and mechanisms of muscle wasting and in the susceptibility of a given fiber type to atrophy. Most likely, the rapid muscle wasting might be in part due to a decrease in protein synthesis coupled with an increased degradation. Besides the quantitative change in muscle mass, age and inactivity induce important qualitative changes in the structure of key skeletal muscle proteins that are manifested in alterations in contractile properties.Therefore, the purpose of this clinical commentary is to identify the major effects of age and inactivity on skeletal muscle structure and function, and discuss potential therapeutic interventions. Special emphasis will be placed on how alterations in muscle structure affect function and on the cellular and molecular mechanisms of the age-related and inactivity-induced muscle changes.

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“…However, in order to study the motional dynamics of myosin heads in the presence of ATP, more precise experimental conditions are required [44].…”

Section: Orientation Order Of Spin Labels In the Presence Of Mgadpmentioning

confidence: 99%

“…In activating solution (buffer A without EGTA plus 5 mM MgATP and 0.1 mM Cazf, 20 mM creatine phosphate, 200 U/ml creatine phosphokinase as ATP regenerating system), the spectral changes at H 11 k orientation were more pronounced. However, in order to study the motional dynamics of myosin heads in the presence of ATP, more precise experimental conditions are required [44].…”

Section: State Ormentioning

confidence: 99%

ADP‐Induced Changes in Ordering of Spin‐Labelled Myosin Heads in Muscle Fibres

Belágyi

Frey

Pótó

1994

European Journal of Biochemistry

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Rotational dynamics and ordering of myosin heads in glycerinated skeletal muscle fibres were studied using an isothiocyanate-based spin label attached to the fast-reacting thiol sites of myosin and were compared with data obtained for maleimide and iodoacetamide spin labels attached to the same sites. The ordering of probe molecules on the millisecond time scale in the rigor state, at sarcomere length 2.2-2.3 ? 0.1 pm, was static. Isothiocyanate probe molecules showed greater mobility; the segment holding the label rotated in the microsecond time range. In the saturation transfer EPR time domain, MgADP did not produce a significant change in the mobility of spin labels.The spectra of isothiocyanate spin-labelled fibres were analyzed in terms of two narrow distributions with mean angles of 75" and 56". In the rigor state, the fractions represented approximately 76% and 24% of the total EPR absorbance. In the presence of MgADP, the conventional EPR spectra showed large changes in the ordering of isothiocyanate probe molecules towards a new distribution, the population with a 6 ' value of 56% increased from 24% to 71% at the expense of the 75% population with no change in the mean angles of the distributions. In the case of maleimide and iodoacetamide spin-labelled fibres, however, the effect of MgADP on the probe angular distribution was small.Tension in muscle is generated by the interaction of myosin with actin, and muscle shortening is the result of thick and thin filaments sliding past one another. Time-resolved Xray diffraction has provided evidence that the changes of the reflection pattern are associated with the movement of crossbridges, and that the time course of the changes correlates with tension development [l]. A different approach for the study of molecular events during muscle contraction is provided by the use of motion-sensitive probe molecules. Paramagnetic and fluorescent labels attached to myosin or actin have recently been used to report molecular motions in protein complexes and muscle fibres [2-51. In glycerinated muscle fibres, paramagnetic probe molecules have a large orientation order with respect to the fibre axis, and in rigor they exhibit very slow motion in the saturation transfer EPR time domain [6, 71. Extended measurements by Thomas et al. [S] have shown that in the presence of ATP or even in rigor, but at a sarcomere length where the overlap of the two sets of filaments is reduced, the heads rotate freely with an effective correlation time in the microsecond time scale.In earlier investigations it was found that the mobility of the 4-iodoacetamido-2,2,6,6-tetramethylpiperidinooxyl (IASL)Correspondence to J. BelBgyi, Central Research Laboratory, University Medical School, H-7643 PCcs, Szigeti ut 12, HungaryAbbreviations. MSL, 4-maleimido-2,2,6,6-tetramethylpiperidinooxyl spin label; IASL, 4-iodoacetamido-2,2,6,6-tetramethylpiperidinooxyl spin label; TCSL, 4-isothiocyanato-2,2,6,6-tetramethylpiperidinooxyl spin label ; Nbs,, 5,5'-dithiobis(2-nitrobenzoic acid) ; ApsA, P',Ps-di(ade...

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Microsecond rotational motion of spin-labeled myosin heads during isometric muscle contraction. Saturation transfer electron paramagnetic resonance

Cited by 50 publications

References 27 publications

Structural change of crossbridges of rabbit skeletal muscle during isometric contraction

Structural change of crossbridges of rabbit skeletal muscle during isometric contraction

Skeletal Muscle Adaptations with Age, Inactivity, and Therapeutic Exercise

ADP‐Induced Changes in Ordering of Spin‐Labelled Myosin Heads in Muscle Fibres

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