In-depth characterisation of the lamb meat proteome from longissimus lumborum

• Lamb longissimus lumborum (48 h post-mortem) proteome was characterised after separating the samples into sarcoplasmic, myofibrillar and insoluble fractions.
• Out of the total 388 ovine-specific proteins found, more than half were identified in the sarcoplasmic fraction.
• About 80% of the identified proteins were based on the protein sequences predicted from the sheep genome.

Lamb is one of the major red meats consumed globally, both as a key component in the diet of some countries, and as a niche meat product in others. Despite this relatively wide consumption, an in-depth description of the global protein composition of lamb has not been reported. In this study, we investigated the proteome of the 48 h post-mortem lamb longissimus lumborum through separation of the samples into sarcoplasmic, myofibrillar and insoluble fractions, followed by an in-depth shotgun proteomic evaluation and bioinformatic analysis. As a result, 388 ovine-specific proteins were identified and characterised. The 207 proteins found in the sarcoplasmic fraction were dominated by glycolytic enzymes and mitochondrial proteins. This fraction also contained several sarcomeric proteins, e.g., myosin light chains and titin. Some of them might be the degradation products from the post-mortem proteolysis. Actin, myosin and tropomyosin were abundant in the myofibrillar fraction while nebulin and titin were also present. Collagen type I, III and IV were found in the insoluble fraction but there were also sequences from myosin and titin. The present study also confirms the existence of at least 300 predicted protein sequences obtained from the latest issue of the sheep genome (version 3) with high confidence.

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