Figure 8

LPC 16:0 position in NPP7 relative to mutated residues. Panel A. Structure shown represents an energy-minimized snapshot from the MD simulation. Distances from sidechains to LPC 16:0 are 2.7 Å (E169 to hydroxyl), 2.9 Å (L107 to choline), 3.0 Å (F275 aromatic centroid to choline), 3.0 Å (F80 to nonpolar tail), 7.2 Å (Y166 to nonpolar tail), and 9.0 Å (Y142 to nonpolar tail). The two distances showing the greatest standard deviations when measured at 1 ps intervals during a 2000 ps simulation trajectory were to F80 (2.0 Å) and to Y166 (1.7 Å). Panel B. Molecular dynamics simulations of the LPC 16:0 complex with NPP7 show dynamic motion of the nonpolar tail within the hydrophobic channel as reflected in the distances between the nonpolar tail and the sidechains of F80 and Y166. This dynamic motion results in close interactions at any given time point with either F80 or Y166.