Oxygen storage and transport proteins

The iron heme protein myoglobin (Mb, MW 17000) is essential for oxygen storage and transport in mammalian... 

Ionic forms of iron (referred to hereafter as iron) also participate in a variety of enzymatic reactions as nonheme irons, which are present as iron-sulfur clusters (e.g., mitochondrial electron transport). There are also both storage and transportable forms of iron that are bound to proteins. Under normal physiological conditions only trace amounts of free iron exist. In the body, if iron exceeds the sequestration capacity of the iron-binding proteins present in different physiological compartments, the free iron can cause tissue damage. Cellular injury is caused by reactive oxygen species that are produced from H2O2 in a reaction catalyzed by iron. Thus, iron homeostasis in the body is in a delicate balance. Either the deficiency or the excess results in abnormalities and presents as a common cause of human diseases. 

Why is myoglobin unsuitable as an O2 transport protein but well suited for O2 storage The relationship between the concentration, or partial pressure, of O2 (PO2) and the quantity of O2 bound is expressed as an O2 saturation isotherm (Figure 6-4). The oxygen-... 

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