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Figure 3.
Figure 3
Stereoviews of the peroxidase and cyclooxygenase active sites. (a) Superposition of the
peroxidase sites of the Fe-PGHS and Mn-PGHS structures. The iron structure is shown in red
and the manganese structure in blue. The protein backbone is represented by the yellow
ribbon. (b) The Mn-PGHS structure, showing the anomalous difference Fourier map contoured
at 6 [89][sigma] . The perspective of the viewer is similar to that in (a), but in (b) the
porphyrin has been rotated slightly upward about a horizontal axis relative to the
orientation shown in (a). (c) Superposition of the NSAID-binding sites of the 2.0 Å
Fe-PGHS and Mn-PGHS structures (Gupta et al., 2004[90] [Gupta, K., Selinsky, B. S., Kaub,
C. J., Katz, A. K. & Loll, P. J. (2004). J. Mol. Biol. 335, 503-518.]-[91][bluearr.gif]
and this work); the color scheme is the same as in (a). The ligand in the Fe-PGHS
structure is [92][alpha] -methyl-4-biphenylacetic acid (desfluoro-flurbiprofen). The
flurbiprofen in the Mn-PGHS structure occupies two alternate positions of roughly equal
occupancy, corresponding to two alternate positions for the F atom. The two fluorine
positions are marked by asterisks. Two alternate rotamers are observed for the side chain
of Ser530 in both the Fe- and Mn-PGHS structures.
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