Characterization and partial sequencing of species-specific sarcoplasmic polypeptides from commercial hake species by mass spectrometry following two-dimensional electrophoresis
C. Pineiro et al., Characterization and partial sequencing of species-specific sarcoplasmic polypeptides from commercial hake species by mass spectrometry following two-dimensional electrophoresis, ELECTROPHOR, 22(8), 2001, pp. 1545-1552
The Merluccidae family comprises marine species, some of them of high comme
rcial value and others less appreciated, whose commercialization in Europe
under the generic name of "hake" is highly remarkable. The potential of pro
teomics was employed in this study with the aim of achieving the differenti
al characterization of five different hake species: Merluccius merluccius (
European hake), M. australis (Southern hake), M. hubbsi (Argentinian hake),
M. gayi (Chilean hake), and M. capensis (Cape hake), some of them very clo
sely related. Species-specific polypeptides were observed for the five hake
species studied in isoelectric focusing (IEF) and/or two-dimensional elect
rophoresis (2-DE) high-resolution gels. The peptide mass maps of two polype
ptide groups, previously selected by 2-DE analysis as potentially species-s
pecific, were obtained by "in-gel" tryptic digestion, followed by matrix as
sisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-
TOF-MS). Analysis of group A polypeptides (with pi in the range of 5.0-5.5
and molecular mass of 17 kDa), allowed the differential classification of t
he hake species into two groups: the East Atlantic coast group and the West
Atlantic coast group. Moreover, the peptide mass-maps from the heat-resist
ant parvalbumin fraction (pl below 4.5; molecular mass < 12 kDa) allowed th
e detection of a peptide characteristic of M. australis not present in the
other four hake species tested. A specific 17 kDa protein from M, merlucciu
s was also partially sequenced by nanospray-ion trap-tandem MS, revealing a
high homology with rat nucleoside diphosphate kinase A (NDKA). This work o
pens the way to the application of proteomics to the differential character
ization of commercial hake species at the molecular level.