Relative contribution of calpain and cathepsins to protein degradation in muscle of sea bass (Dicentrarchus labrax L.)

Abstract

The effects of a milli(m)-calpain isolated from the white muscle of sea bass (Dicentrarchus labrax L) and commercial cathepsins B, D and L, used in combination on the myofibrillar and sarcoplasmic proteins were examined. Protein digestion was first performed by the endogenous m-calpain, during 2 h before the addition of a mixture of cathepsins B, D and L and a further incubation up to 22 h. Calpain degraded a 27 kDa sarcoplasmic component as well as myosin heavy chain, α-actinin, desmin and a 32 kDa component from the myofibrillar fraction. A 97 kDa component and the assumed creatine kinase-aldolase doublet were degraded during the incubation of sarcoplasmic proteins with the cathepsin mixture while, among the myofibrillar proteins, myosin, actin, tropomyosin, and the 22 kDa component were digested by the same enzymatic preparation. Myofibril-bound α-actinin and tropomyosin were released into the soluble fraction by m-calpain and the cathepsins mixture. Some smaller fragments were also produced. This appears to be the result of the cumulative action of each protease, as already investigated in our previous studies, except for the degradation of the sarcoplasmic 97 kDa component. It was only degraded if the cathepsins were mixed; this indicates that the three cathepsins functioned synergistically on muscle proteins. No difference in the proteolytic effect of cathepsins was observed, whether calpain was acting first or not. This work showed that calpain did not modify any muscle protein prior to later hydrolysis by the catheptic proteinases.

The Electrophoretic Profile Myofibrillar Proteins Extracted From Camel Muscles, Kept in Various Modes

“…The appearance of bands at 33 kDa indicator of tenderness were also reported by Ho et al, [25] and Zamora et al, [26] on beef and Smili, [27] on camel meat. The lower molecular weight bands at 23 kDa for the muscles having undergone or not before refrigeration acid treatment consistent with the results of Chobert et al, [28]; Cho, [29]; Barany et al, [30], Delbarre-Ladrat et al, [21] and Ouali et al, [20] on beef. The use of organic acids (citric and lactic acids) accelerated proteolysis myofibrillar proteins, thus leading to early proteolysis, which can induce a tenderizing meat.…”

“…The bands identified one hour after slaughter were had molecular weights of 66, 53, 42, 36, 33, 18, 16 and 14 KDa. According to the work of Delbarre-Ladrat et al, [21] and Bond et al, [22], these bands were identified as tropomyosin, desmin, actin (AC), tropomyosin (TMP), Troponin I, Troponin C and two light chains myosin (MLC), respectively. Starting from hours post-mortem, the strips 66 and 48 kDa disappeared as well as the bands of relative molecular weights of the order of 42, 36, 33, 26 and 23 kDa, have been identified and the molecular weight bands 13, 14, 16, 18 and 97 kDa.…”

Texture characteristics of chilled prepared Mandarin fish (Siniperca chuatsi) during storage

“…[41] Previous studies showed that degradation of myosin and actin was primarily associated with cathepsin, but cathepsin was not activated during early storage. [42] Through the weakening of Z-disks, release of costameres, breakdown of desmin and dystrophin, loss of α-actinin, and proteolysis of nebulin, titin and troponin-T, calpains play a leading role in early storage. [41,43] Therefore, the quality deterioration of Mandarin fish during their shelf life at 4°C is mainly due to the degradation of low-abundance proteins, including desmin, dystrophin, and α-actinin.…”

Proteomics in Food Science

“…Postmortem proteolytic tenderization of muscle tissue is, together with bacterial spoilage, one of the most adverse changes related to fish freshness and quality and has therefore been widely studied. Postmortem proteolysis mainly affects myofibrillar and cytoskeletal proteins such as titin, nebulin, dystrophin, ␣-actinin, myosin, and tropomyosin (Verrez-Bagnis et al, 1999;Delbarre-Ladrat et al, 2004;Caballero et al, 2009;Du et al, 2010;Wu et al, 2010). Various endogenous proteolytic enzymes seem to be involved, including cathepsins, calpains, aminopeptidases, and connective tissue hydrolases (Delbarre-Ladrat et al, 2006).…”