Figure 3

Residue replacements of whale myoglobin during the evolution from the terrestrial animal to sperm whale. (a) Amino-acid sequence alignment of ancestral and sperm whale Mbs. Amino acid replacements on aMbWp to aMbWb’, aMbWb’ to aMbWb, and aMbWb to swMb are meshed with light brown, light green, and light blue, respectively. The residues in the canonical helices A – H are boxed. (b) The replaced residues are shown on the crystal structures of aMbWp (PDB code 5YCG), aMbWb’ (5YCI and 5YCJ), aMbWb (5YCH), and swMb (5YCE). The canonical helices A – H are indicated on the structure of aMbWp.  (c) V13I, T34K, and K118R and E27D are replacements from aMbWp (light brown) to aMbWb’ (light green). (d) G1V and G15A are those from aMbWb’ to aMbWb (light blue). (e) D4E, V28I, N12H, K45R, and D109E are from aMbWb to swMb (blue). The electrostatic interactions/hydrogen bonds and cavity filling positions are indicted with the yellow dotted lines and red circles, respectively. The green arrows indicate alternative conformations.