Figure 9

SM position in NPP7 relative to mutated residues. Structure shown represents an energy-minimized snapshot from the MD simulation. Distances from sidechains to SM are 2.4 Å (Y166 to sphingoid tail), 2.5 Å (L107 to choline), 2.9Å (E169 to palmitoyl tail), 3.7 Å (F275 aromatic centroid to choline), 5.5 Å (Y142 to sphingoid tail), and 6.9 Å (F80 to sphingoid tail). Mutation of F141 (yellow) to serine was reported by Duan, et al. to substantially reduce sphingomyelinase activity of NPP7 [15]. Distance between F141 and the palmitoyl tail is 2.8 Å.