Detailed Structures of Hemoglobins and Model Systems

With thermodynamic background and general structural features relevant to ligand affinity enumerated, attention may now be turned to the detailed structural aspects of the active site and its surroundings. As was shown crudely in Figure 4.3, the ligand affinity of an iron porphyrin may be perturbed either by modulating the structure of the deoxy material or by modulating the structure and surroundings of the liganded material or both. The model systems provide the reference points against which the protein structures may be compared.