Figure 2
Tyrosine at position 3 affects Arg8 (stereoviews). (a) Superposition of cQYN (pink C atoms) and F3Y, where the alanine at position 9 (A9) is substituted by Arg (R9) (light blue C atoms), superimposed on the cQFD meditope (green C atoms). The presence of a hydroxyl from Tyr3 (Y3) sterically occludes the Arg8 side chain, resulting in the loss of a hydrogen bond to the backbone of Gln111 in the heavy chain. The hydroxyl group of Y3, however, leads to the coordination of a water molecule. (b) Superposition of the Fab (cQFD in black and cQYN in pink) shows that the hydroxyl substitution leads to a slight reorientation of the meditope with respect to the Fab. |