Due to the constant demand by the consumers in to know the quality and the origin of seafood products and to the news commercial regulations imposed by many countries all over the world, important efforts in our laboratory have been focused on the application of proteomics tools for the identification of two closely-related hake species (Merluccius capensis and Merluccius paradoxus). Both species also called as Cape hakes present similar iporphological features and coexist in the same catch area overlapping their geographical distribution in the coast of South Africa. The main of the goal of the present work is to characterize species-specific peptides to discriminate both species using new strategies based on proteomics tools, mainly by means of mass spectrometry (MS). Sarcoplasmic protein extracts were obtained from both hake species and resolved by two-dimensional gel electrophoresis (2-DE). A characteristic protein spot was selected, digested in gel with trypsin and subjected to analysis by MS in an ion trap mass spectrometer. Spectra results were analyzed and compared by searching in the protein database using several programs like Mascot and Sequest. In addition de nova peptide sequencing was also performed manually and using DeNovoX software. The results obtained by LC-MS/MS show that the characteristic spot that difference both species correspond to the aldolase protein. Specific peptide spectra from aldolase were interpreted using several programs and the results show several species-specific peptides that were considered as potential biomarkers. Amino acids substitution in the sequences corresponding to the same specific peptides clearly indicated several potential molecular markers. The development of the specific antibodies for these peptide biomarkers could provides in a further a simple, fast and straightforward method for the routine species discrimination of both species

37th WEFTA Annual Meeting, Lisbon, Portugal, 24 -26 October 2007

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