Sperm whale myoglobin, schematic

Figure 2. A schematic diagram of sperm whale myoglobin. Cylinders represent a-helices. Figures 1 and 2 show the molecule in the same orientation, looking into the heme pocket.

Figure 14. Schematic representation of sperm whale myoglobin showing the ruthenated histidines 12, 48, 81, and 116, and the heme with its axial histidine. The edge-edge ET distances are shown for each histidine (118).

Fig. 10. Schematic conformation of sperm whale myoglobin after Kendtew et al. (48). The sausage is the protein chain, which is mostly in the a-hdical conformation. The heme group is held in a cleft by apolar contacts, and by two histidine side chmns. Three or four other histidine side chains participate in the fcxmaticm the folded protein structure. Since the side chain of histidine contains an imidazole ring, a free side chain can be protonated at low pH (the pK is ca. 6.5). However, the five or six buried side chains cannot be protonated, and hence the overall equilibrium constant for unfolding is strongly pH dependent in first approximation (34)...

Fig. 2.14 Schematic structure of the myoglobin of the sperm whale. The arrow indicates the wireframe model of heme with the attached oxygen molecule redballs), the blue ribbons represent the globin protein. (Authors own work and copyright-free Wikipedia picture)...

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