Journal of agricultural and food chemistry | 2019
Expression of pork plectin during postmortem aging.
Abstract
The current study investigated the distribution and degradation of pork plectin during postmortem aging. Longissimus thoracis (LT) muscles from 12 pig carcasses were vacuum packaged and aged at 4°C for 0 h, 6 h, 12 h, 1 d, 3 d, 7 d and 13 d. Immunofluorescence analysis showed that pork plectin was distributed in a honeycomb-like pattern in cross section and a regularly striated pattern in longitudinal section. However, plectin was found preferentially expressed in fibers which were stained with high anti fast-MyHC. Double immunostaining revealed the colocalization of plectin and desmin in the cytoplasm and beneath the sarcolemma. Western blot analysis showed that the amount of intact plectin was rapidly reduced during the early postmortem aging (P < 0.05) and almost disappeared at d 3. The degraded 240 kDa plectin accumulated fast and was further cleaved after 3 d aging (P < 0.05). The plectin degradation could be significantly blocked by calpain inhibitor MDL-28170 rather than caspase-3 inhibitor Ac-DEVD-CHO (P < 0.05). Double immunostaining of µ-calpain and plectin showed a large amount of overlap at 0 h and 3 d postmortem. Accordingly, these findings showed that plectin was preferentially expressed in fast muscle fiber and regularly distributed along with desmin at the strategic cellular sites. Plectin suffered a prominent and prompt degradation during postmortem aging which might be attributed to µ-calpain.