The primary structure of myoglobin from yellowfin tuna (Thunnus albacares)

The amino acid sequence of myoglobin from yellowfin tuna (Thunnus albacares) has been determined. The globin is an aminoacetylated chain containing 146 residues and having deletions, with respect to mammalian and avian myoglobins, at the NH2 terminus and two internal locations. From 79 to 85 amino acid substitutions are observed between this myoglobin and those of mammals, birds, and shark. Two external regions containing 6 and 7 residues, which are highly conserved in mammalian and avian myoglobins, are greatly or totally altered in the tuna sequence. Significant differences are apparent in the extent of electrostatic bonding in the myoglobins of fish and in those of mammals or birds.