Chicken muscle, rigor

Fig. 15. Stereo views of the different myosin head, SI, structures showing their variable conformations in different crystal structures. (A) The heads with their motor domains superimposed and oriented as if interacting with a vertical actin filaments in the rigor conformation, Z-band bottom and M-band top. (B) The same structures in a view down the actin filament long axis, looking from the M-band towards the Z-band. Blue is the Dominguez et al. (1998) structure of SI in chicken smooth muscle with ADP.AIF4 bound, orange is the insect flight muscle SI in the ADP.Pj state (Al-Khayat et al., 2003), yellow is scallop SI crystal structure in the ADP.VO4 state (Houdusse et al., 1999), and green is the chicken skeletal muscle with no nucleotide bound (Rayment et al., 1993a).

Fig. 31. Implications about the contractile mechanism in insect flight muscle. Blue is insect flight muscle SI shape in pre-powerstroke state (Al-Khayat et al., 2003), and green is chicken skeletal muscle SI in the rigor state with no nucleotide bound (Rayment et al., 1993a). The actin filament (right) is shown with the Z-band at the bottom and M-band at the top. A transition from the pre-powerstroke/resting SI shape to the rigor/end of post-powerstroke shape would involve an axial swing of the lever arm by 100 A, resulting in the sliding of the actin filaments past the myosin filaments and toward the M-band.

The onset of rigor mortis occurs in beef muscle within 10-24 h in pork, 4-18 h and in chicken, 2-4 h. 

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