Details of quinine binding. Quinine complexes with Fab 314.1 (A) and Fab 314.3 (B). Quinine is shown in thicker stick with wheat carbons; Fab CDR loops and framework are shown in thinner stick with silver carbons. Oxygens are red and nitrogens are blue. Fabs are shown with white transparent surfaces. 2Fo-Fc quinine omit map density is shown as magenta mesh contoured at 3σ. Interactions between quinine and Fab 314.1 (C) and Fab 314.3 (D) shown schematically with Maestro (Schrodinger, New York, NY). Hydrophobic residues are shown in green, hydrophilic residues are cyan, positively charged residues are violet, negatively charged residues are pink, and glycine residues are white. Stripes show backbone contact regions. Arrows show hydrogen bonds. Green line shows π-π stacking. Red-blue line shows a salt bridge. Red curved lines show π-cation interaction. Shadows on atoms in quinine schematize their amount of exposure to solvent. Comparisons for Fab 314.1 (E) and Fab 314.3 (F) with and without quinine. Carbons for the Fabs are shown in silver (no quinine) and in cyan (with quinine).