Primary and secondary structure of antifreeze peptides from arctic and antarctic zoarcid fishes.

Antifreeze peptides were isolated from Rhigophila dearborni, an antarctic eel pout, and Lycodes polaris, an arctic eel pout (both from the family Zoarcidae). The primary structures of two peptides, one from each species, were determined using a combination of Edman degradation and mass spectrometric techniques. The two sequences show a high degree of homology with nearly 80% of the residues being identical. These peptides are also homologous to antifreeze peptides from a third eel pout which inhabits the north Atlantic Ocean. The CD spectra of all of these peptides are also very similar. Unlike the antifreeze peptides of cottid fishes, the structures of antifreeze peptides from zoarcid fishes appear to be highly conserved, despite the large geographic distances which separate the different species. The zoarcid peptides also appear to have structures very different from other fish antifreezes.