Myoglobin Interaction with small molecules

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... 

Redox proteins are relatively small molecules. In biological systems they are membrane associated, mobile (soluble) or associated with other proteins. Their molecular structure ensures specific interactions with other proteins or enzymes. In a simplified way this situation is mimicked when electrodes are chemically modified to substitute one of the reaction partners of biological redox pairs. The major classes of soluble redox active proteins are heme proteins, ferredoxins, flavoproteins and copper proteins (Table 2.1). In most cases they do not catalyze specific chemical reactions themselves, but function as biological (natural) electron carriers to or between enzymes catalyzing specific transformations. Also some proteins which are naturally not involved in redox processes but carry redox active sites (e.g., hemoglobin and myoglobin) show reversible electron exchange at proper functionalized electrodes. 

The analysis of myoglobin suggests that the native structure of a protein is often such that the small molecules that interact with the protein cannot enter or leave if the atoms are constrained to their average positions. Consequently, side chain and other fluctuations may be required for ligand binding by proteins and for the entrance of substrates and exit of products from enzymes. 

---