title: Effect of inhibition of μ-calpain on the myofibril structure and myofibrillar protein degradation in postmortem ovine muscle.
abstract: BACKGROUND
  Tenderness is considered to be one of the most important attributes of meat quality. Myofibrillar protein degradation contributes to meat tenderization during postmortem ageing. In this process, calpain is the primary enzyme catalyzing the proteolysis. To further understand the action of calpain in meat tenderization, a μ-calpain inhibitor, MDL-28170, was used and its effects on sarcomere structure and myofibrillar protein degradation were determined.
  
  
  RESULTS
  The results of the present study showed that inhibition of μ-calpain significantly reduced muscle myofibrillar fragmentation compared to the group without μ-calpain inhibitor. Meanwhile, the sarcomere structure of the μ-calpain inhibited muscle was only slightly broken and largely remained integral 48 h postmortem. Myosin heavy chain, actin, desmin, troponin T and troponin I were identified to be substrates of μ-calpain by liquid chromatography-tandem mass spectrocopy and western blotting, and were detected with a higher degradation degree in the control group compared to the μ-calpain inhibition group.
  
  
  CONCLUSIONS
  Comparatively, myosin heavy chain and actin were found to be less sensitive to μ-calpain compared to desmin, troponin T and troponin I. These findings provide a better understanding of the contribution of μ-calpain to the myofibril structure and myofibrillar protein degradation of ovine muscle. © 2016 Society of Chemical Industry.
authors: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing, 100193, PR China.
authors: Zheng
authors: Z
authors: Li
authors: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing, 100193, PR China.
authors: Xin
authors: X
authors: Li
authors: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing, 100193, PR China.
authors: Xing
authors: X
authors: Gao
authors: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing, 100193, PR China.
authors: Manting
authors: M
authors: Du
authors: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing, 100193, PR China.
authors: Dequan
authors: D
authors: Zhang
mesh_terms: D000818:Animals; D055162:Biocatalysis; D002154:Calpain / Q000737:chemistry* / Q000378:metabolism; D004338:Drug Combinations; D008460:Meat / Q000032:analysis; D009124:Muscle Proteins / Q000737:chemistry*; D018482:Muscle, Skeletal / Q000737:chemistry* / Q000378:metabolism; D009210:Myofibrils / Q000737:chemistry* / Q000378:metabolism; D010206:Papain / Q000737:chemistry* / Q000378:metabolism; D011180:Postmortem Changes; D059748:Proteolysis; D012756:Sheep; D012982:Sodium, Dietary / Q000378:metabolism
chemical_list: D004338:Drug Combinations; D009124:Muscle Proteins; D012982:Sodium, Dietary; C032508:meat tenderizer; D002154:Calpain; C449002:mu-calpain; D010206:Papain
keywords: myofibril structure; myofibrillar proteins; protein degradation; μ-calpain