Fig. 2.
X-ray crystal structure of the LT1009 Fab:S1P complex. (A) A ribbon diagram representation of the antibody Fab fragment. The light chain is colored gold and the heavy chain is brown. S1P is depicted as a ball-and-stick model with cpk coloring and the 2 Ca2+ ions are represented as light gray spheres. (B) Close-up view of the S1P binding site. Electron density from a 2 FO - FC refined map contoured at 1.1 σ is displayed for the region of the model within 1.9 Å of each atom in S1P. (C) A semitransparent surface representation of the Fab reveals the extent to which S1P, represented as cpk spheres, is buried upon binding to LT1009.