Muscle rigor

A number of attempts to trap heads in the elusive AM.ADP.Pj state in intact muscle, sometimes using ATP analogues (e.g., AMP.PNP), as well as 

Stereo-specifically attached heads as in rigor give rise to a mixed population of myosin-like and actin-like layer lines, including a 143 A (M3) reflection. They show good evidence for actin target areas. 

Non-stereo-specifically attached (such as weak-binding) heads, even though on actin, give a myosin-like layer line pattern including a 143 A (M3) reflection. This also includes a contribution to the first myosin layer line (ML1) and the first actin layer line (Al Ferenczi et al, 2005 Harford and Squire, 1992 Xu et al., 1999). 

In active or rigor muscle, heads that do not overlap actin filaments become disordered (Cantino et al, 2002 Padron and Craig, 1989). They therefore contribute little to the observed low-angle X-ray diffraction patterns. This population increases with increasing sarcomere length (reduced filament overlap). 

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X-ray diffraction of live muscle (H.E. Huxley and Brown, 1967) showed the structure of the thick and thin filaments and how they changed when the muscle contracted, or was put into rigor (in rigor muscle, ATP is absent from the muscle. 

Several groups have studied the effects on the muscle low-angle diffraction pattern of applying various mechanical perturbations to steady-state structures, either isometric contractions or rigor muscle at various strain levels. Huxley et al. (1981, 1983) used whole frog muscles and followed the effects of step changes of length of various amplitudes applied at the plateau of an otherwise isometric tetanus. They studied the effects on the M3 intensity as a whole. More recendy, with the two components of the active M3 resolved, Huxley et al. (2003) and Reconditi et al. (2003) have studied the separate behavior of these components. Huxley et al. (2003) found that the intensity ratio of the M30 to M3 varied from an initial value... 

Huxley, H. E. (1968). Structural difference between resting and rigor muscle evidence from intensity changes in the low-angle equatorial X-ray diagram./. Mol. Biol. 14, 507-520. 

Millman, B. M., and Irving, T. C. (1988). Filament lattice of frog striated muscle. Radial forces, lattice stability, and filament compression in the A-band of relaxed and rigor muscle. Biophys.J. 54, 437-47. 

Reconditi, M., Koubassova, N., Linari, M., Dobbie, I., Narayan, T. Diat,0., Piazzesi, G., Lombardi, V., and Irving, M. (2003). The conformation of myosin head domains in rigor muscle determined by X-ray interference. Biophys.J. 85, 1098-1110. 

Kennick, W.H., Elgasim, E.A., Holmes, Z.A., and Meyer, P.R 1980. The effect of pressurization of pre-rigor muscle on post-rigor meat characteristics. Meat Science 4 33 0. 

R. Cooke, Stress Does Not Alter the Conformation of a Domain of the Myosin Cross Bridge in Rigor Muscle Fiber, Nature 294, 570 (1981). 

Salt measurements on the samples showed that the samples had a salt content between 0.3 and 0.4%. When salt was added by salt injection the salt content of the wild post rigor group increased to 0.6% NaCl, but no significant change was found in the salt content for salt injected farmed or wild pre rigor samples. This indicated that only the wild post rigor muscle had an effective salt uptake in the study. 

The chemical spoilage indicators of total volatile base nitrogen (TVB-N) and trimethylamine (TMA) first became evident in the chilled samples on storage days 9-13 and not until on day 15 for superchilled pre rigor muscle (both salted and non salted). It could therefore be seen that superchilling had a positive effect on the slowing down the spoilage of the fish. 

Compound pmol/g Fresh tissue living post-rigor muscle muscle ... 

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