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Figure 5.
The role of NADP^+ in the stabilization of
C4a-hydroperoxyflavin intermediate. (A) Modeling experiment in
which the hypothetical structure of C4a-hydroperoxyflavin was
superimposed to the flavin in mFMO structure. The color code is
the same as in Fig. 4B. Hypothetical hydrogen bonds involving
the hydroperoxyflavin atoms are shown as blue dashed lines. The
accommodation of the additional oxygen atoms of the C4a-adduct
would require a shift of ≈1.5 Å of Asn-78 side chain
(whose conformation in the native structure is shown as thin
black stick). (B) Comparison of the NADP^+-binding mode in S.
pombe (Protein Data Bank ID code 2gv8) and Methylophaga FMOs.
The picture was obtained by superimposing the Cα atoms of the
two proteins and shows the FAD (yellow) and NADP^+ (blue)
molecules of mFMO together with FAD and NADP^+ of the S. pombe
enzyme (red). The N5 and C4a atoms of the flavin and C4 and C2
atoms of NADP^+ are labeled.
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