Fig. 3.

Crystal structure of SidF. (A and B) Two orthogonal views of the crystal structure of SidF represented in ribbons. The catalytic “CX₅R” motif is shown in spheres and indicated by an arrow. Two loops that protrude out from a flat surface (the bottom surface in A and C) are highlighted with a square and colored in gold. (C and D) Two orthogonal views of the crystal structure of SidF represented in surface. The surfaces are colored based on electrostatic potential with positively charged regions in blue (+4 kcal per electron) and negatively charged surface in red (−4 kcal per electron). C and D have an identical orientation as in A and B, respectively. Note that the catalytic motif is localized in a highly basic groove.