Studies have suggested that the phenomenon of dark cutting (Canada B4) beef may also be related to muscle glycolytic proteins. The objective of this study, therefore, was to analyze longissimus thoracis (LT; n = 23), from Canada AA (n = 8), atypical (AB4; pH < 5.9, n = 8) and typical (TB4; pH > 5.9, n = 7) B4 heifer and steer carcasses, for sarcoplasmic and myofibrillar proteins using 2-D gel electrophoresis and LC-MS/MS mass spectrometry. Results indicated that AB4 LT had intramuscular pH and lactate concentration similar to Canada AA but lower (P < 0.05) L* and b*. Moreover, AB4 LT were tougher than Canada AA even at 21 days post-mortem, unlike TB4. Canada AB4 LT had reduced (P < 0.05) levels of creatine kinase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase and glycerol-3-phosphate dehydrogenase [NAD(+)], indicating a compromised glycolytic capacity in AB4. Canada AB4 LT had increased (P < 0.05) abundances of phosphatidylethanolamine-binding protein 1 and small heat shock proteins.

研究表明，牛肉暗切现象（加拿大B4）也可能与肌肉糖酵解蛋白有关。因此，本研究的目的是分析 加拿大AA（n  = 8），非典型（AB4； pH <5.9，n  = 8）和典型值（TB4； pH> 5.9）的长经胸（LT；n = 23）。 ，n  = 7）B4小牛和ste体，使用2-D凝胶电泳和LC-MS / MS质谱分析肌浆蛋白和肌原纤维蛋白。结果表明AB4 LT的肌内pH和乳酸浓度与Canada AA相似，但L *和b *较低（P  <0.05）。而且，与TB4不同，即使在死后21天，AB4 LT也比加拿大AA更为坚韧。加拿大AB4 LT 的肌酸激酶，甘油醛3磷酸脱氢酶，乳酸脱氢酶和甘油3磷酸脱氢酶[NAD（+）]水平降低（P <0.05），表明AB4中的糖酵解能力受到损害。加拿大AB4 LT 的磷脂酰乙醇胺结合蛋白1和小的热休克蛋白的丰度增加了（P <0.05）。