Discrimination of South African Commercial Fish Species (Merluccius capensis and Merluccius paradoxus) by LC-MS/MS Analysis of the Protein Aldolase

Abstract

Analysis of the protein aldolase using proteomic methodologies allowed the discrimination of the Cape hakes, Merluccius capensis and Merluccius paradoxus. A classical bottom-up proteomics approach, consisting of two-dimensional gel electrophoresis, tryptic in-gel digestion, and LC-MS/MS analyses, was performed for the characterization and de novo sequencing of the aldolase spots. The sequences discovered presented a high degree of homology with the aldolase A sequence from the teleostei Tetraodon nigroviridis. De novo sequencing of several MS/MS spectra from the aldolase A spots allowed the characterization of two species-specific peptide biomarkers. One of them was unique to Merluccius capensis while the other was present only in Merluccius paradoxus. These peptide biomarkers can be used to discriminate between both species of Cape hakes.

KEYWORDS:

• proteomics
• aldolase
• hake
• two-dimensional gel electrophoresis
• mass spectrometry
• de novo sequencing

The authors thank Freiremar S.A. for their assistance in the collection of Cape hakes used in this study. This work was supported by the Comisión Interministerial de Ciencia y Tecnología (CICyT; Project AGL2000-0440-P4-02). B. C. is supported by the Ramón y Cajal program (RYC-2003) under the auspices of the Spanish Ministry of Science and Technology.