The onset of rigor mortis and its resolution partially determines the tenderness of meat. ![]() Rigor mortis is very important in the meat industry. ĭecomposition of the myofilaments occurs between 48 and 60 hours after the peak of rigor mortis, which occurs approximately 13 hours after death. As part of the process of decomposition, the myosin heads are degraded by the enzymes, allowing the muscle contraction to release and the body to relax. However, as ATP is absent, there must be a breakdown of muscle tissue by enzymes (endogenous or bacterial) during decomposition. Normal relaxation would occur by replacing ADP with ATP, which would destabilize the myosin-actin bond and break the cross-bridge. In rigor mortis myosin heads continue binding with the active sites of actin proteins via adenosine diphosphate (ADP), and the muscle is unable to relax until further enzyme activity degrades the complex. Once calcium is introduced into the cytosol, it binds to the troponin of thin filaments, which causes the troponin-tropomyosin complex to change shape and allow the myosin heads to bind to the active sites of actin proteins. The calcium activates the formation of actin-myosin cross-bridging. Also, the breakdown of the sarcolemma causes additional calcium to enter the cytosol. Calcium is released into the cytosol due to the deterioration of the sarcoplasmic reticulum. ![]() When the body's glycogen is depleted, the ATP concentration diminishes, and the body enters rigor mortis because it is unable to break those bridges. When oxygen is no longer present, the body may continue to produce ATP via anaerobic glycolysis. ATP is required to cause separation of the actin-myosin cross-bridges during relaxation of muscle. Corpses of victims of the 1991 Bangladesh cyclone in Sandwip displaying signs of rigor mortisĪfter death, aerobic respiration in an organism ceases, depleting the source of oxygen used in the making of adenosine triphosphate (ATP).
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