This improvement is due to the activities of calpains
, cathepsins, proteasome, and caspases during the early postmortem period [21, 22].
In AD brain, calpastatin levels are found to be significantly decreased and calpains
activity is aberrantly enhanced.
The increased intracellular calcium leads to (a) activation of the nitric oxide synthetase (NO) leading to cerebral edema and ischemia; (b) activation of casplases (destructive enzymes) that damage the DNA of the cell, leading to apoptosis; (c) activation of the proteases family of calpains
, which cause the breakdown of the neuronal cytoskeleton leading to the loss of structural integrity of the neuron; (d) damage to the Na/K pump, leading to an influx of additional sodium followed by water with resultant cerebral edema; and (e) mitochondrial injury leading to reactive oxygen species generation, microvascular damage, and cerebral edema (Huh, Franklin, Widing, & Raghupathi, 2006; Robertson, Bucci, & Fiskum, 2004; Robertson, Saraswati, & Fiskum, 2007).
NAC maybe able to maintain the activity of Na+/K+ pump in muscle due to a redox-dependent [64, 65] attenuation of sarcoplasmic reticulum injury  that results in a lower calcium release and thus a reduced activity of muscle's proteolytic proteins such as the proteosome and calpains
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).
Proteolytic enzymes such as cathepsins and calpains
are involved in structural and biochemical changes during post mortem ageing process (Ouali et al.
Role of calpains
in postmortem proteolysis in chicken muscle.
17) Proteins that compose the calcium network undergo oxidative modification through time, resulting in conformational changes, aggregation, and internalization from the plasma membrane and proteolytic degradation by the calcium-activated calpains
Some chemical compounds already exist that block the activity of calpains
, although the researchers do not yet know the exact function of calpain
14, as very little has been published about it.
2003) The calpains
in aging and aging related diseases.
Cell death can be classified according to its morphological appearance (which may be apoptotic, necrotic, autophagic or associated with mitosis), enzymological criteria (with and without the involvement of nucleases or of distinct classes of proteases, such as caspases, calpains
, cathepsins and transglutaminases), functional aspects (programmed or accidental, physiological or pathological) or immunological characteristics (immunogenic or nonimmunogenic).
Aside from being a good inhibitor, the stabilized alpha-helical molecule is also highly specific for calpains
, while ignoring other, similar-shaped proteases, thus hopefully downplaying potential side effects if used in humans.