Oxidation-induced unfolding facilitates Myosin cross-linking in myofibrillar protein by microbial transglutaminase.
Myofibrillar protein from pork Longissimus muscle was oxidatively stressed for 2 and 24 h at 4 °C with mixed 10 μM FeCl(3)/100 μM ascorbic acid/1, 5, or 10 mM H(2)O(2) (which produces hydroxyl radicals) and then treated with microbial transglutaminase (MTG) (E:S = 1:20) for 2 h at 4 °C. Oxidation induced significant protein structural changes (P < 0.05) as evidenced by suppressed K-ATPase activity, elevated Ca-ATPase activity, increased carbonyl and disulfide contents, and reduced conformational stability, all in a H(2)O(2) dose-dependent manner. The structural alterations, notably with mild oxidation, led to stronger MTG catalysis. More substantial amine reductions (19.8-27.6%) at 1 mM H(2)O(2) occurred as compared to 11.6% in nonoxidized samples (P < 0.05) after MTG treatment. This coincided with more pronounced losses of myosin in oxidized samples (up to 33.2%) as compared to 21.1% in nonoxidized (P < 0.05), which was attributed to glutamine-lysine cross-linking as suggested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
Chunqiang
C
Li
Youling L
YL
Xiong
Jie
J
Chen
D000818:Animals; D003432:Cross-Linking Reagents; D005511:Food Handling; D017665:Hydroxyl Radical / Q000737:chemistry; D008460:Meat; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000737:chemistry; D009210:Myofibrils / Q000737:chemistry* / Q000378:metabolism*; D009218:Myosins / Q000737:chemistry*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D058767:Protein Unfolding; D013552:Swine; D011503:Transglutaminases / Q000378:metabolism*
D003432:Cross-Linking Reagents; D009124:Muscle Proteins; D017665:Hydroxyl Radical; D011503:Transglutaminases; D009218:Myosins