Fig. 14.

The comparison of the active site geometry of four liganded high resolution TIM structures, suggesting how a sliding motion of the Glu167 side chain over the catalytic end of the substrate could facilitate the proton shuttling by the catalytic base. The structures concern the complexes with PGH (2VXN) (purple), 2PG (1N55) (green), DHAP (1NEY) (orange), and IPP (1IF2) (cyan). In the PGH complex, the side chain is near Cys126, Ala165, Leu232, and in the IPP complex it is nearest to Ile172