State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
J Agric Food Chem. 2012 Aug 15;60(32):8020-7. doi: 10.1021/jf302150h. Epub 2012 Jul 31.
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.
猪背最长肌肌原纤维蛋白在 4°C 下用混合 10 μM FeCl(3)/100 μM 抗坏血酸/1、5 或 10 mM H(2)O(2)（产生羟基自由基）氧化应激 2 和 24 h，然后用微生物转谷氨酰胺酶（MTG）（E：S = 1:20）在 4°C 下处理 2 h。氧化诱导了显著的蛋白质结构变化（P < 0.05），这表现在 K-ATP 酶活性受到抑制、Ca-ATP 酶活性升高、羰基和二硫键含量增加以及构象稳定性降低，所有这些变化都呈 H(2)O(2)剂量依赖性。结构变化，特别是轻度氧化，导致 MTG 催化作用增强。与非氧化样品（P < 0.05）相比，在 1 mM H(2)O(2)下，MTG 处理后，胺还原量显著增加（19.8-27.6%），而非氧化样品中为 11.6%。这与氧化样品中肌球蛋白的明显损失（高达 33.2%）一致，而非氧化样品中为 21.1%（P < 0.05），这归因于谷氨酰胺-赖氨酸交联，正如十二烷基硫酸钠-聚丙烯酰胺凝胶电泳所表明的那样。
