Metals and oxygen: respiration, oxidation, and oxygen toxicity

Abstract Aerobic respiration is the process by whichO2 is used to oxidize foodstuffs (fats, carbohydrates, proteins) and produce heat and other forms of energy such as ATP. Because O2 is poorly soluble in water, the major constituent of the human body † we have evolved a transport protein to carry it, haemoglobin in the red blood cells (Figure 1). Haemoglobin has four protein subunits. To each is bound a complex chemical structure (haem), at the centre of which is an iron ion, in the ferrous (Fe2+) state. Oxygen reversibly binds to this iron, giving a Fe2+— O2 complex (causing the bright red colour of oxygenated blood).