Abstract: The peptide mass fingerprints of actin from Siniperca chuatsi, Trachinotus ovatus and Acipenser sinensis were analyzed by Orbitrap Fusion Lumos mass spectrometry. The differences in the amino acid sequence and the signature peptides of actin from the three fishes were clarified. Results showed that the signature peptides were identified in the enzymatic hydrolysate of skeletal muscle α-actin for S. chuatsi, while the signature peptides were derived from β-actin for both T. ovatus and A. sinensis. Totally 29 peptides were detected in S. chuatsi actin, 24 peptides in T. ovatus actin, all being the signature peptides, and 13 peptides in A. sinensis actin. Compared with the actin fingerprints of the two other fishes, 10 differential peptides were identified in skeletal muscle α-actin of S. chuatsi, five differential peptides in β-actin of T. ovatus, and only three differential peptides in β-actin of A. sinensis. According to the arrangement of amino acid sequences, there were 21 amino acid substitutions between S. chuatsi skeletal muscle α-actin and T. ovatus β-actin, starting from the similar sequences, and 17 amino acid substitutions between S. chuatsi skeletal muscle α-actin and A. sinensis β-actin. The amino acid sequences of A. sinensis and T. ovatus β-actin showed high homology to each other with only three amino acid substitutions. The results of this study will lay a foundation for the identification of quality properties of rare fish and the development of fish actin standards, and provide a theoretical basis for the development, utilization and rapid quantitative detection of functional fish protein products.

Key words: Orbitrap Fusion Lumos mass spectrometry; fish actin; peptide mass fingerprint; difference