FIGURE 2.

8R-LOX with AA. A, ribbon drawings of 8R-LOX with (blue) and without (gray) AA in the active site. Fe²⁺ is shown as a red sphere. The helical insertion described in all LOX structures is shown in violet. B, detail of the outward shift of the arched helix observed in the presence of AA. C, an omit map contoured +2/−2σ (green/magenta) reveals clear electron density for AA. D, the steady state rate dependence on substrate concentration of 8R-LOX and the mutant R182A. 8R-LOX data were fit to the Michaelis-Menten equation, whereas the R182A data were fit to Equation 1. Equation 1 describes cooperative substrate inhibition for the fit, n = 2.4 ± 0.3.