Figure 7 - full size

 

Figure 7.
Figure 7. The conformation of loop aL6 is determined by the position of an arginine residue. (a) In a-TRPS, the guanidinium group of aArg179 lies in the plane of the loop and forms a number of radial interactions. (b) In BX1 the corresponding guanidinium group, Arg266, is tilted out of the ring plane, resulting in only one interaction with the loop. The two guanidinium groups occupy similar positions in space.

The above figure is reprinted by permission from Elsevier: J Mol Biol (2005, 352, 608-620) copyright 2005.