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Lysosomal Enzyme Effects on the Postmortem Changes in Tilapia ( Tilapia nilotica X T. aurea ) Muscle Myofibrils
Author(s) -
JIANG SHANNTZONG,
WANG YUHTAI,
CHEN CHINGSAN
Publication year - 1992
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1992.tb05475.x
Subject(s) - myofibril , cathepsin l , cathepsin , fragmentation (computing) , biochemistry , enzyme , proteolysis , chemistry , cathepsin b , cathepsin d , tilapia , biology , fish <actinopterygii> , fishery , ecology
To investigate the effects of lysosomal proteases on myofibril fragmentation, tilapia ( Tilapia nilotica X T. aurea ) muscle myofibrils were incubated with isolated lysosomal fraction containing 12 units of cathepsin D/mL (G‐II) and pure cathepsin D (12 units/mL G‐III) at pH 5.5, 6.0, and 6.5 for 3 days at 4°C. Among samples incubated at pH 5.5, the degree of myofibril fragmentation (DMF) of G‐III was highest, while, at pH 6.0 and 6.5, that of G‐II was highest. At pH 6.5, the higher DMF of G‐III than that of G‐I suggested that cathepsin D still had proteolytic activity on myofibrils. Difference in the decrease of protein content between G‐III and G‐I, and between G‐II and G‐I indicated that proteolysis caused by cathepsin D was highest at pH 5.5, while that caused by lysosomal enzymes was highest at pH 6.5. This suggested the participation of lysosomal enzymes in the fragmentation of myofibrils.