Effect of Postmortem Storage on Degradation of the Myofibrillar Protein Titin in Bovine <i>Longissimus</i> Muscle

Abstract

ABSTRACT Purified bovine longissimus muscle myofibrils were prepared from muscle at death and from muscle samples stored at 2°, 25°, or 37°C for 1, 3, and 7 days postmortem. Tbe myofibrils were analyzed by sodium dodecyl sulfate‐polyacrylamide slab gel electrophoresis. Titin migrated as a closely spaced doublet of very high molecular weight (M r ∼ 1 × 10 6 ) in myofibrils from at‐death muscle samples. With increased storage time and temperature, the top band of the titin doublet gradually disappeared. the lower doublet band (putative breakdown product of upper band) remained after 7 days storage at 2° or 25°C, but disappeared by 3 days of postmortem storage at 37°C. Thus, titin is degraded in postmortem muscle, and the rate of degradation is enhanced by increases in storage time and temperature.