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EFFECTS OF MUSCLE PROTEASES, ENDOGENOUS PROTEASE INHIBITORS AND MYOFIBRIL FRAGMENTATION ON POSTMORTEM AGING OF GOAT MEAT
Author(s) -
NAGARAJ N.S.,
SANTHANAM K.
Publication year - 2006
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.2006.00066.x
Subject(s) - calpastatin , myofibril , calpain , titin , proteolysis , cathepsin , cathepsin b , chemistry , cystatin , longissimus , cystatin c , nebulin , cathepsin d , proteases , biochemistry , protease , protein degradation , enzyme , biology , sarcomere , microbiology and biotechnology , anatomy , myocyte , renal function
ABSTRACT The present study was conducted to evaluate the extent of postmortem proteolysis in longissimus dorsi , biceps femoris , semimembranosus and semitendinosus goat muscles on postmortem aging at an ambient (27C) temperature. The activities of calpains and calpastatin were determined after separation on a (diethylamino)ethyl–Sephacel column (Sigma, St. Louis, MO) and cathepsin (B, B + L and H) by carboxymethyl–Sepharose column (Sigma). The results showed that the decrease in calpain I and calpastatin activities was significantly higher than that of calpain II. Cathepsin B, B + L, H and cystatin were found to fall by 30–80% after 12 h, whereas cathepsin D decreased significantly in all the muscles. The disappearance of titin 1 and nebulin, and the appearance of a 30‐kDa component were confirmed by Western blot analysis. The appearance of the 30‐kDa component reported here explains the time‐induced structural changes of myofibrils. The Z‐line degradation had occurred by 6 h postmortem. Cathepsins are not stable compared to calpains during postmortem aging, and both enzymes may play a significant role in the proteolysis of myofibrillar proteins at ambient temperature.