FIGURE 5.

Structural comparison of the heme pocket of sperm whale Mb and of horse heart Mb. (A) Overlapping of residues Leu²⁹, Lys (Arg)⁴⁵, Phe⁴⁶, His⁶⁴, Val (Thr)⁶⁷, Val⁶⁸, and Leu⁸⁹ in the proximity of the heme for sperm whale Mb (dark sticks) and horse heart Mb (light sticks). The H bond of Arg⁴⁵ with heme-6-propionate is shown. (B) Comparison of the solvent-accessible surface for the side chains of residues Lys (Arg)⁴⁵, His⁶⁴, Val (Thr)⁶⁷, and Val⁶⁸ of the Fe(III) forms of sperm whale Mb (right) and horse heart Mb (left) distal pocket (SWMb, Protein Data Bank code 1VXG; HHMb, Protein Data Bank code 1WLA). Molecular graphics images were produced using the UCSF Chimera package (23). For further details see text.