The autolysis of meat occurs with the active participation of lysosome enzymes-cathepsins and calpains
(i) Inactivation of endogenous proteases, especially calpains
(the most important being [micro]-calpain): these enzymes need a reducing substrate to carry out their action, given the presence of functional groups -SH (thiols) which are subject to oxidation; however, the role of this mechanism is debated, as some authors highlighted the marginal role of calpains
in meat tenderization [35, 72].
Greer, "Ubiquitous calpains
promote caspase-12 and JNK activation during endoplasmic reticulum stress-induced apoptosis," The Journal of Biological Chemistry, vol.
, skeletal muscle function and exercise," Clinical and Experimental Pharmacology and Physiology, vol.
Enzymes such as caspases, calpains
, thrombin, and cathepsins cleave tau. Experiments in vitro indicate that caspases 1, 3, 6, 7, and 8 can cleave tau at different sites, resulting in the generation of truncated tau species which are primed for subsequent phosphorylation., Calpain
activity is regulated by a calcium-dependent heat-stable inhibitor, calpastatin.
superfamily is complex, and more than 25 calpains
or calpain-like molecules have been discovered.
As excessive myoplasmic [Ca.sup.2+] concentration activates calpains
that cleave a variety of substrates, including myofibrillar proteins [24, 29, 30], calpain-mediated degradation could contribute to the ultrastructural alterations observed in [RYR1.sup.Y522S/WT] muscle fibers.
are a family of calcium-activated cysteine proteases that catalyze the limited proteolysis of a number of cellular proteins in eukaryotes [18, 19].
The calpastatin (CAST) which has been found in all the tissues that contain calpains
, is a specific inhibitor of calpain
enzymes (Lonergan et al., 2010).
This axonal disintegration process is mediated by the activation of calcium-dependent proteases, such as calpains
, that target cytoskeleton proteins, especially neurofilaments, for degradation (10).
Therefore, a greater proportion of oxidative fibers reflect in lower activity of calpains
, due to a larger amount of calpastatin, resulting in lower muscle degradation and originating a less tender meat (Koohmaraie, 1996).