Figure 7.

Crystal structure of avian FPP synthase, an isologous dimer of 44-kD subunits, was the first to reveal the α fold of a class I terpenoid synthase. The active site of each monomer opens toward the top and is partially capped by loops and additional helices (yellow and red cylinders). Helices in one subunit are labeled by capital letters, and helices in the other subunit are labeled by primed capital letters. Active sites are oriented in parallel fashion (i.e., the active sites of the left and right subunits open to the top of the figure). Reproduced from ref (58). Copyright 1994 American Chemical Society.