Abstract
Supplementation of vitamin E improves beef colour stability by minimizing lipid oxidation-induced myoglobin oxidation. Mitochondria affect myoglobin redox stability, and dietary vitamin E influences mitochondrial functionality in skeletal muscles. Nonetheless, the influence of vitamin E on the mitochondrial proteome of beef skeletal muscles has yet to be investigated. Therefore, the objective of this study was to examine the effect of dietary vitamin E on mitochondrial proteome of post-mortem beef longissimus lumborum (LL) muscle. Beef LL muscle samples (24 hours post-mortem) were obtained from the carcasses of nine (n = 9) vitamin E-fed (VITE) (1000 IU vitamin E for 89 days) and nine (n = 9) control (CONT) (diet without supplemental vitamin E) heifers. The mitochondrial proteome was analysed using two-dimensional gel electrophoresis and mass spectrometry, and nine differentially abundant spots were identified. All the differentially abundant spots were over-abundant in CONT, and the proteins were electron transport chain enzymes (NADH dehydrogenase iron-sulphur protein 8, NADH dehydrogenase flavoprotein 2, and cytochrome c oxidase subunit 5B), metabolic enzymes (succinate-CoA ligase (ADP-forming) subunit beta; dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex; pyruvate dehydrogenase protein X component), and enzymes involved in ATP regeneration (creatine kinase S-type). The low abundance of these proteins in VITE may decrease mitochondrial activity, resulting in low oxidative activity. These findings suggest that the strong antioxidant activity of vitamin E leads to less expression of mitochondrial oxidative enzymes in beef skeletal muscles. Keywords : Beef colour, lipid oxidation, mitochondrial enzymes
Highlights
Mitochondria are the main organelles that consume oxygen and synthesize ATP, in living cells and in post-mortem skeletal muscles
The results of the present study indicated that mitochondria from longissimus lumborum (LL) muscle of heifers supplemented with vitamin E demonstrated lower abundance of enzymes involved in the electron transport chain, tricarboxylic acid cycle, pyruvate metabolism, and ATP regeneration, compared with mitochondria from heifers that did not receive vitamin E supplementation (VITE)
Low abundance of enzymes generating reactive oxygen species could lead to low lipid oxidation in beef from vitamin E-supplemented cattle. These findings indicated that dietary vitamin E appears to influence mitochondrial proteome of beef LL by decreasing mitochondrial activity and decreasing oxidative stress
Summary
Mitochondria are the main organelles that consume oxygen and synthesize ATP, in living cells and in post-mortem skeletal muscles. Intact and functionally active mitochondria can be isolated 45 days post-mortem from beef muscles (Tang et al, 2005a). Fresh meat colour is influenced by mitochondrial activity mainly through two mechanisms: oxygen consumption and metmyoglobin reducing activity. The excessive oxygen consumption by mitochondria hinders initial bloom development and red colour intensity by competing with myoglobin for available oxygen (Wittenberg & Wittenberg, 2007). Mitochondrial activity is one of the most important endogenous factors that influence fresh meat colour (Mancini & Hunt, 2005; Suman & Joseph, 2013; Suman et al, 2014; Neethling et al, 2017; Ramanathan & Mancini, 2018)
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