Figure 9.

Sketch of the catalytic cycle of FAD synthases. In the figure the schematic representation of FAD synthesis performed by hFADS6 (orange boxes) or hFADS6-D238A (blue boxes), and next cofactor delivery to client apo-flavoprotein (green boxes). Both recombinant proteins show the same catalytic cycle, in addition, several differences are highlighted in the picture: in the mutant, the increased K_ms for substrates ATP and FMN (in the forward reaction) and PPi and FAD (in the reverse reaction) are highlighted by increasing font size; the increased k_cat in the mutant is highlighted by decreasing arrow length in the last step from the enzyme-FAD (E-FAD) complex to free enzyme (E); the increased ability, in the mutant, to deliver the cofactor to client apo-flavoprotein is highlighted by decreasing arrow length from the enzyme-FAD (E-FAD) complex to product FAD. This picture is based on results obtained with the isoform 2 in [17] and with D238A-hFADS6 in this work.