Complete amino acid sequence of the myoglobin from the Dall porpoise (Phocoenoides dalli dalli) and reinvestigation of the primary structure of the myoglobin from common porpoise (Phocoena phocoena).

Abstract

The complete amino acid sequence of the principal component myoglobin of the Dall porpoise, Phocoenoides dalli dalli, was determined by specific cleavage of the protein to obtain large peptides which are readily degraded by the au- tomatic sequencer. The apomyoglobin was selectively cleaved at the two methionine residues with cyanogen bromide and the acetimidated apomyoglobin was cleaved at the three arginine residues by trypsin. Over 80% of the primary structure of the protein was obtained by subjecting four of these peptides and the apomyoglobin to automatic Edman degradation. The re- mainder of the primary structure was determined by sequence analysis of tryptic peptides isolated from the central cyanogen This paper reports the use of the automatic Edman degra- dation procedure in determining the complete amino acid se- quence of the myoglobin from the Dall porpoise, Phocoenoides dalli dalli. The peptide fragmentation and the analytical procedures necessary for this determination have been estab- lished in several other cetacean myoglobin sequence papers (Dwulet et al., 1975, 1977; Bogardt et al., 1976; Jones et al., 1976, 1978; Lehman et al., 1977; Wang et al., 1977; DiMarchi et al., 1978). The sequence reported here differs in only two residue positions from that reported for the common porpoise, Phocoena phocoena (Bradshaw & Gurd, 1969). A direct comparison by identical methods of the properties of samples of these proteins available to us has failed to show any differ- ence between the myoglobins of these two species and raises the question of a possible error in the previous determination of the common porpoise sequence.