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Figure 4.
Fig. 4. Ball-and-stick, wall-eyed stereodiagram figure of
the active site. This wall-eyed stereodiagram emphasizes the
stereochemical relationships of the three cofactors, one as
lysyl-PLP external aldimine. The C5' carbon of SeSAM where
radical initiation will occur is 3.8 Å from C3 of the
lysyl side chain. The conserved Arg-134 denies rotation around
the C1-C2 bond of lysyl moiety. Asp-293 interacts with both the
 -amino group of lysine
and N1 of the purine ring of SeSAM, and Asp-330 is in
hydrogen-bonded contact with the -amino group. SeSAM is
ligated to the unique iron in the [4Fe-4S] cluster through the
selenomethionyl  -amino and carboxylate
groups. See Fig. 8 for detailed interactions within the active
site. Hydrogen atom positions are provided for reference based
on theoretical constraints only and are not determined by the
diffraction data.
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