Superoxide dismutase topology

Figure 4.10 (a) The Cu-Zn superoxide dismutase is made up of eight anti-parallel P-strands both the constant (b) and variable (c) domains of immunoglobulins are made up of seven anti-parallel P-strands with the same topology the variable domain contains two additional P-strands. (From Branden and Tooze, 1991. Reproduced by permission of Garland Publishing, Inc.)... 

The commonest subgroup of antiparallel /3 barrel structures has a Greek key topology, with -3,+1,+1,-3 connections or a close variant. The first Greek key barrel structures were compared in Richardson et al. (1976), and they and the up-and-down barrels were described as categories in Richardson (1977). Figure 96 illustrates Cu,Zn superoxide dismutase as an example of a Greek key j8 barrel. 

Although the details of the structure of superoxide dismutase (SOD), one form of which is a Cu,Zn-enzyme (Cu,Zn-SOD), have been well described previously (Getzoff etal., 1983), a brief description is repeated here, for the geometry of the copper site as well as the topology of its fold is relevant to all copper enzymes. 

Fig. 8. (a) Copper and zinc sites in superoxide dismutase (SOD). The small sphere is waterbound to the copper site, (b) Ribbon drawing of the SOD backbone, (c and d) Schematic of SOD topology. 

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