Effect of postmortem storage on the Z-line region of titin in bovine muscle.
Myofibrils were prepared from bovine muscles (cutaneous trunci, rectus abdominis, psoas major, and masseter) and compared between different aging periods at 4 degrees C (0, 1, 2, 4, 8, and 16 d). Myofibrils were stained with an antibody directed against a 56-kDa fragment (FE-RE) of titin located in the Z-line region. Unaged myofibrils from all four muscles showed a single stained band at the Z-line with similar intensities. Postmortem time did not significantly affect the total amount of fluorescence in the sarcomere, suggesting the titin FE-RE epitope was not degraded nor were titin fragments containing this epitope released during storage. However, the fluorescence patterns were altered. The relative fluorescence intensity at the Z-line decreased but that in the I-band increased gradually, showing the translocation of some titin FE-RE epitopes during the aging period. This suggested that a cleavage occurred in a region of titin very close to the Z-line during postmortem storage. Usually the position of maximum fluorescence remained at the Z-line, although about 1/3 of the myofibrils from rectus abdominis showed a two-band pattern around the Z-line after 16 d of aging. The titin changes observed may be related to the increased fragility of the myofibril and the improvement of meat tenderness during postmortem storage.
Boyer-Berri
C
C
Muscle Biology Laboratory, University of Wisconsin-Madison, 53706, USA.
Greaser
M L
ML
D000818:Animals; D002417:Cattle; D002645:Chickens; D064211:Connectin; D000939:Epitopes / Q000276:immunology; D007106:Immune Sera / Q000276:immunology; D008297:Male; D008406:Masseter Muscle / Q000276:immunology / Q000473:pathology; D051379:Mice; D009124:Muscle Proteins / Q000032:analysis*; D018482:Muscle, Skeletal / Q000276:immunology / Q000473:pathology*; D009210:Myofibrils / Q000737:chemistry* / Q000276:immunology; D011180:Postmortem Changes; D011494:Protein Kinases / Q000032:analysis*; D016658:Psoas Muscles / Q000276:immunology / Q000473:pathology; D011817:Rabbits; D017568:Rectus Abdominis / Q000276:immunology / Q000473:pathology; D013997:Time Factors
D064211:Connectin; D000939:Epitopes; D007106:Immune Sera; D009124:Muscle Proteins; D011494:Protein Kinases