Figure 3.

Cartoon drawings of E. coli OTCase catalytic trimer ligated with the bisubstrate analog PALO, shown as a space filling model. These figures were generated by graphic programs molscript (57) and render (58, 59). Chain A1, A2, and A3 are colored light blue, blue, and green respectively. (Upper) Top view, down the molecular three-fold axis. CP and l-ornithine binding domains of chain A1 are labeled. One active site, shared between chain A1 and the 80s loop of chain A2, is also labeled. (Lower) Side view, perpendicular to the three-fold axis. N/C termini and α helices 1, 7, 8a, and 9a of chain A2 are labeled.