Complete amino acid sequence of the myoglobin from the Atlantic bottlenosed dolphin, Tursiops truncatus

Abstract

The complete amino acid sequence of the major component myoglobin [Mb] from T. truncatus was determined by specific cleavage of the protein to obtain large peptides that are readily degraded by the automatic sequencer. Three easily separable peptides were obtained by cleaving the protein with cyanogen bromide at the 2 methionine residues and 4 peptides were obtained by cleaving the methyl acetimidated protein with trypsin at the 3 arginine residues. By subjecting 4 of these peptides and the apomyoglobin to automatic Edman degradation, over 80% of the covalent structure of the protein was obtained. The remainder of the primary structure was determined by further digestion of the central cyanogen bromide peptide with trypsin and staphylococcal protease. This Mb differs from that of the sperm whale Physter catodon at 15 positions, from that of the California gray whale Eschrichtius gibbosus at 14 positions, from that of the common porpoise Phocoena phocoena at 6 positions, and from the Mb of the Black Sea dolphin Delphinus delphis and the Amazon River dolphin Inia goeffrensis, at 5 and 7 positions, respectively. All substitutions observed in this sequence fit easily into the tertiary structure of sperm whale Mb.