| Budget Amount *help |
¥21,000,000 (Direct Cost: ¥21,000,000)
Fiscal Year 1993: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1992: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1991: ¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 1990: ¥9,000,000 (Direct Cost: ¥9,000,000)
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| Research Abstract |
1. alpha-Connectin, which forms very thin filaments in myofibrils, was non-enzymatically split into beta-connectin and a 1,200-kDa subfragment during post-mortem ageing of meat. The splitting was induced by the binding of calcium ions to the beta-connectin portion of alpha-connectin, and reached a maximum at 0.1 mM Ca^<2+>. The 1,200-kDa subfragment was about 0.34 mum apart from the Z-disk, and bound to alpha-actinin. 2. Nebulin filaments which adhere to thin (actin) filaments, were fragmented into 200-, 180-, 40-, 33- and 23-kDa subfragments during post-mortem ageing of meat. All the subfragments except the 180-kDa one were released from myofibrils. The fragmentation of nebulin filaments was non-enzymatically induced by the binding of calcium ions to the 200-, 40- and 23-kDa subfragments, and reached a maximum at 0.1 mM Ca^<2+>.3. The rate of the post-mortem translocation of paratropomyosin from the A-I junction region of sarcomeres onto the thin filaments in the A-band, where rigor linkages had been formed, agreed well with the rate of increase in length of rigor-shortened sarcomeres : The sarcomere lengths were found to be maximum at 1, 7 and 10 days post-mortem in chicken, pork and beef, respectively. Those rates are quite consistent with the well-known periods required for post-mortem ageing to tenderize chicken, pork and beef. 4. Phospholipids existed in the Z-disk of skeletal muscle myofibrils, and constituted its amorphous matrix. The content of phospholipids was about 1 g per 100 g of myofibrillar proteins. The phospholipids were released from the Z-disk in a precise agreement with the Z-disk weakening during post-mortem ageing of meat. On the other hand, the amount of alpha-actinin remained unchanged during post-mortem ageing of meat, indicating that calpain does not take part in the post-mortem weakening of Z-disks. 5. These results powerfully support the "Calcium theory of meat tenderization" which I have proposed, and object the assumption t
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