Journal article
Head Rotation or Dissociation?: A Study of Exponential Rate Processes in Chemically Skinned Rabbit Muscle Fibers When MgATP Concentration Is Changed
Biophysical journal, Vol.22(1), pp.97-103
04/1978
DOI: 10.1016/S0006-3495(78)85473-3
PMCID: PMC1473409
PMID: 638228
Abstract
The mechanical response of fully activated muscle bundles (one to five fibers) to sinusoidal length perturbation (∼0.4%
L
0
) was studied as a function of MgATP concentration. The frequency response (0.25-167 Hz; corresponding to 1 ms time resolution) of chemically skinned rabbit muscle fibers was resolved into three exponential rate processes, (A), (B), and (C). At 20°C, the apparent rate constants associated with the fast exponential lead (2π
c
= 388-588 s
-1
) and the oscillatory work (2π
b
= 59-116 s
-1
) both increase with increment of the MgATP concentration from 1 to 5 mM, and they both saturate for further increase. Over the whole range of MgATP concentrations the slow exponential lead (2π
a
= 9-7 s
-1
) remains constant. The effect of MgATP on processes (B) and (C) can be interpreted in the context of the biochemical evidence, in which MgATP enters the cross-bridge cycle after the desorption of the product, and the binding of MgATP to rigorlike cross-bridges promotes a rapid dissociation of actomyosin (Lymn and Taylor, 1971.
Biochemistry.
10:
4617-4624.). The effect is not predicted by a model for force generation in which head rotation dominates the fast component (“stage 2” of Huxley and Simmons, 1971.
Nature (Lond.).
233:
533-538. and 1973.
Cold Spring Harbor Symp. Quant. Biol.
37:
669-680.), and head dissociation dominates the slow component (“phase 4” of Huxley, 1974.
J. Physiol. (Lond.).
243:
1-43; Julian et al., 1974.
Biophys. J.
14:
546-562.).
Details
- Title: Subtitle
- Head Rotation or Dissociation?: A Study of Exponential Rate Processes in Chemically Skinned Rabbit Muscle Fibers When MgATP Concentration Is Changed
- Creators
- Masataka Kawai
- Resource Type
- Journal article
- Publication Details
- Biophysical journal, Vol.22(1), pp.97-103
- DOI
- 10.1016/S0006-3495(78)85473-3
- PMID
- 638228
- PMCID
- PMC1473409
- NLM abbreviation
- Biophys J
- ISSN
- 0006-3495
- eISSN
- 1542-0086
- Language
- English
- Date published
- 04/1978
- Academic Unit
- Anatomy and Cell Biology; Internal Medicine
- Record Identifier
- 9984025678702771
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