The effect of inorganic phosphate on the ATP hydrolysis rate and the tension transients in chemically skinned rabbit psoas fibers

Kawai, Masataka; Güth, K.; Winnikes, K.; Haist, C.; Rüegg, J. C.

doi:10.1007/bf00581833

Cited by 114 publications

(110 citation statements)

References 43 publications

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“…This confirms an earlier study in detail (19). Usefully, this pattern of coupling mirrors the P i sensitivity of phase 2 slow ; P i sensitivity is apparent in slow-(34) and medium-speed fibers (35), but not fast fibers (18,36). This correlation locates P i release before tension generation with step 6 reversible in all but fast fibers.…”

Section: L-jump Kinetics and The Cross-bridge Cyclesupporting

confidence: 86%

Mechanistic role of movement and strain sensitivity in muscle contraction

Davis

Epstein

2009

Proc. Natl. Acad. Sci. U.S.A.

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Tension generation can be studied by applying step perturbations to contracting muscle fibers and subdividing the mechanical response into exponential phases. The de novo tension-generating isomerization is associated with one of these phases. Earlier work has shown that a temperature jump perturbs the equilibrium constant directly to increase tension. Here, we show that a length jump functions quite differently. A step release (relative movement of thick and thin filaments) appears to release a steric constraint on an ensemble of noncompetent postphosphate release actomyosin cross-bridges, enabling them to generate tension, a concentration jump in effect. Structural studies [Taylor KA, et al. (1999) Tomographic 3D reconstruction of quick-frozen, Ca 2؉ -activated contracting insect flight muscle. Cell 99:421-431] that map to these kinetics indicate that both catalytic and lever arm domains of noncompetent myosin heads change angle on actin, whereas lever arm movement alone mediates the power stroke. Together, these kinetic and structural observations show a 13-nm overall interaction distance of myosin with actin, including a final 4-to 6-nm power stroke when the catalytic domain is fixed on actin. Raising fiber temperature with both perturbation techniques accelerates the forward, but slows the reverse rate constant of tension generation, kinetics akin to the unfolding/folding of small proteins. Decreasing strain, however, causes both forward and reverse rate constants to increase. Despite these changes in rate, the equilibrium constant is strain-insensitive. Activation enthalpy and entropy data show this invariance to be the result of enthalpyentropy compensation. Reaction amplitudes confirm a strain-invariant equilibrium constant and thus a strain-insensitive ratio of pretension-to tension-generating states as work is done.enthalpy-entropy compensation ͉ length step ͉ non-Arrhenius ͉ protein folding ͉ tension generation T he question of how the many asynchronously operating myosin motors generate tension and movement in muscle fibers is a critical issue in biology. Two different mechanisms have been proposed. In one, thermal fluctuations in position enable myosin heads (cross-bridges) to bind actin in a strained configuration to generate tension (1, 2). This rectification process can occur between detached and attached heads or by heads changing angle between subsites while attached to actin. For these thermal ratchet models to function at physiological rates, a sequence of multiple attached states is generally required, the stiffer the cross-bridge the larger the number of states. Heterogeneous mechanisms, some with sequential temperature-sensitive and -insensitive tension-generating transitions, have also been invoked (3-5). Power stroke mechanisms in which tension generation occurs as a single-step conformational change in attached cross-bridges offer an alternative mechanism e.g. (6-10). Other important aspects include the relationship between intermediate states of the ATPase cycle and tension generation....

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Section: L-jump Kinetics and The Cross-bridge Cyclesupporting

confidence: 86%

Mechanistic role of movement and strain sensitivity in muscle contraction

Davis

Epstein

2009

Proc. Natl. Acad. Sci. U.S.A.

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“…We are learning that a more complete contractile apparatus better recapitulates the cellular phenotype produced by mutations in regulatory proteins (11,20,32,34). As shown by Güth and Potter (18) and others (36,37), when ADP is added to the solution, the equilibrium shifts toward strongly bound crossbridge states, and the apparent Ca 2ϩ sensitivity increases. Others (18, 36 -39) have shown that adding P i to the solution shifts the equilibrium toward detached cross-bridge states and a decrease in the apparent Ca 2ϩ sensitivity.…”

Section: Discussionmentioning

confidence: 88%

Strong Cross-bridges Potentiate the Ca2+ Affinity Changes Produced by Hypertrophic Cardiomyopathy Cardiac Troponin C Mutants in Myofilaments

Pinto

Reynaldo

Parvatiyar

et al. 2011

Journal of Biological Chemistry

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This spectroscopic study examined the steady-state and kinetic parameters governing the cross-bridge effect on the increased Ca 2؉ affinity of hypertrophic cardiomyopathy-cardiac troponin C (HCM-cTnC) mutants. Previously, we found that incorporation of the A8V and D145E HCM-cTnC mutants, but not E134D into thin filaments (TFs), increased the apparent Ca 2؉ affinity relative to TFs containing the WT protein. Here, we show that the addition of myosin subfragment 1 (S1) to TFs reconstituted with these mutants in the absence of MgATP 2؊ , the condition conducive to rigor cross-bridge formation, further increased the apparent Ca 2؉ affinity. Stopped-flow fluorescence techniques were used to determine the kinetics of Ca 2؉ dissociation (k off ) from the cTnC mutants in the presence of TFs and S1. At a high level of complexity (i.e. TF ؉ S1), an increase in the Ca 2؉ affinity and decrease in k off was achieved for the A8V and D145E mutants when compared with WT. Therefore, it appears that the cTnC Ca 2؉ off-rate is most likely to be affected rather than the Ca 2؉ on rate. At all levels of TF complexity, the results obtained with the E134D mutant reproduced those seen with the WT protein. We conclude that strong cross-bridges potentiate the Ca 2؉ -sensitizing effect of HCM-cTnC mutants on the myofilament. Finally, the slower k off from the A8V and D145E mutants can be directly correlated with the diastolic dysfunction seen in these patients.

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“…It is of note that the lactate release is of equal magnitude at 3-4 and 7-8 min at 50 W. The magnitude of the anaerobic contribution is a minimum value as some accumulation of lactate may also occur at the 'steady-state' phase at this exercise intensity. The possibility exists that this anaerobic energy yield from glycolysis compensates for a reduction in free energy (AG) from ATP hydrolysis when increases take place in factors such as temperature and Pi and reduction in pH (Kawai, Guth, Winnikes, Haist & Ruegg, 1987; Cooke, Franks, Luciani & Pate, 1988). If this assumption is correct, one would have anticipated that the same would occur during the intense exercise, i.e.…”

Section: Discussionmentioning

confidence: 99%

Anaerobic energy production and O2 deficit‐debt relationship during exhaustive exercise in humans.

Bangsbo¹,

Gollnick²,

Graham³

et al. 1990

The Journal of Physiology

298

248

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SUMMARY1. Eight subjects performed one-legged, dynamic, knee-extensor exercise, first at 10 W followed by 10 min rest, then at an intense, exhaustive exercise load (65 W) lasting 3-2 min. After 60 min recovery, exercise was performed for 8-10 min each at 20, 30, 40 and 50 W. Measurements of pulmonary oxygen uptake, heart rate, blood pressure, leg blood flow, and femoral arterial-venous differences of oxygen content and lactate were performed as well as determination of ATP, creatine phosphate (CP) inosine monophosphate (IMP) and lactate concentrations on biopsy material from the quadriceps muscle before and immediately after the intense exercise, and at 3, 10 and 60 min into recovery.2. Individual linear relations (r = 0-95-1-00) between the power outputs for submaximal exercise and oxygen uptakes (leg and pulmonary) were used to estimate the energy demand during intense exercise. Pulmonary and leg oxygen deficits determined as the difference between energy demand and oxygen uptake were 0-46 and 0-48 1 (kg active muscle)-', respectively. Limb and pulmonary oxygen debts (oxygen uptake during 60 min of recovery -pre-exercise oxygen uptake) were 0-55 and 1P65 1 (kg active muscle)-', respectively. J. BANGSBO AND OTHERS for less than 10 % of the leg oxygen debt, and lactate elimination including resynthesis of glycogen for another 25 %. 5. The anaerobic energy contribution during the first half-minute of intense exercise accounted for 80 % of the total energy turnover and this decreased to 30 % during the last phase of the exercise. The mean anaerobic energy contribution was 45 % for the 3-2 min of exhaustive exercise.6. The maximal anaerobic capacity of human muscle amounted to the equivalent of close to 051 02 kg-1. An extrapolation to whole-body anaerobic capacity cannot be made, as the magnitude of neither [ATP] and [CP] reduction nor lactate release from the muscle is likely to be comparable in all muscles when the human performs whole-body exercise.7. When exercising with a small muscle group the measurements of (i) oxygen deficit and (ii) energy yield, based on metabolic alterations of the active muscle, give similar values for the anaerobic energy release. The dominant fraction of the elevation in recovery oxygen uptake (i.e. oxygen debt) is not accounted for, as normalization of nucleotides, CP, muscle and blood lactate only amounted to about 3 of the debt measurement. Elevation in hormones such as adrenaline and noradrenaline as well as temperature do not appear to play a role in the high recovery oxygen uptake in the present study.

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The effect of inorganic phosphate on the ATP hydrolysis rate and the tension transients in chemically skinned rabbit psoas fibers

Cited by 114 publications

References 43 publications

Mechanistic role of movement and strain sensitivity in muscle contraction

Mechanistic role of movement and strain sensitivity in muscle contraction

Strong Cross-bridges Potentiate the Ca2+ Affinity Changes Produced by Hypertrophic Cardiomyopathy Cardiac Troponin C Mutants in Myofilaments

Anaerobic energy production and O2 deficit‐debt relationship during exhaustive exercise in humans.

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