Oxygen myoglobin and

Each heme unit in myoglobin and hemoglobin contains one ion bound to four nitrogen donor atoms in a square planar arrangement. This leaves the metal with two axial coordination sites to bind other ligands. One of these sites is bound to a histidine side chain that holds the heme in the pocket of the protein. The other axial position is where reversible binding of molecular oxygen takes place. 

Synthetic models of myoglobin and hemoglobin are complex molecules that mimic the stereochemical properties of the protein active center [24] and have oxygen affinities similar to those measured for the protein [25-27]. The first heme model that reversibly binds oxygen (i.e. the picket-fence-oxygen complex Fe(TpivPP)(l,2-Melm)(02), shown in Fig. 3.3) was obtained in the early nine-teen-seventies by Collman and coworkers (TpivPP = tetrapivalami-nophenyl porphyrin 2-meIm = 2-methylimidazole) [18]. Research on synthetic models of the protein has led to a deeper understand-... 

Figure 13.5 (a) The structure of sperm whale myoglobin. (From Voet and Voet, 2004. Reproduced with permission from John Wiley Sons., Inc.) (b) The oxygen-binding curves of myoglobin and haemoglobin. (Reprinted with permission from Collman et al., 2004. Copyright (2004) American Chemical Society.)... 

The interaction of Fe(II) with small molecules has received much attention. The Fe(II)/ oxygen system must be one of the most studied chemical interactions. Since the Fe-porphyrin complex forms the core of the naturally occurring iron respiratory proteins myoglobin and... 

---