Copper-containing dioxygen carriers

Copper has an essential role in a number of enzymes, notably those involved in the catalysis of electron transfer and in the transport of dioxygen and the catalysis of its reactions. The latter topic is discussed in Section 62.1.12. Hemocyanin, the copper-containing dioxygen carrier, is considered in Section 62.1.12.3.8, while the important role of copper in oxidases is exemplified in cytochrome oxidase, the terminal member of the mitochondrial electron-transfer chain (62.1.12.4), the multicopper blue oxidases such as laccase, ascorbate oxidase and ceruloplasmin (62.1.12.6) and the non-blue oxidases (62.12.7). Copper is also involved in the Cu/Zn-superoxide dismutases (62.1.12.8.1) and a number of hydroxylases, such as tyrosinase (62.1.12.11.2) and dopamine-jS-hydroxylase (62.1.12.11.3). Tyrosinase and hemocyanin have similar binuclear copper centres. 

Hemocyanins (He), the copper-containing dioxygen carriers, are distributed erratically in two large phyla, Mollusca (for example, octopi and snails) and... 

The second class of dioxygen carriers is that of haemocyanins. These proteins, which contain a binuclear Cu(I) site (thus in the oxidized Cu(II) met form they belong to the so-called Type 3 copper proteins , which contain an EPR-silent dicopper active site), regulate dioxygen transport in the respiration of arthropods and molluscs. Figures 7 and 8 show... 

Tyrosinase is the oldest known monooxygenase that catalyzes monophenol oxidation to quinone [34, 109]. It contains a dinuclear copper site which is very similar to that found in hemocyanin, a ubiquitous oxygen carrier for invertebrates [110-112]. The dioxygen adduct of tyrosinase is known to exhibit unusual spectral characteristics which are similar to those of the dioxygen adduct of hemocyanin (1) unusually low v(O-O) assignable to a symmetric peroxide ascertained by resonance Raman spectroscopy [113], (2) unique intense absorption bands seen at 350 nm ( , -20000 cm M ) / 2Cu and ca. 580 nm... 

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