Figure 2.

Position of the redox-sensitive buried crystal water W166 (see text) relative to the heme iron during the simulations. (A) Dots: radial distribution function g(r) of water oxygens around the heme iron (scaled arbitrarily for clarity); g(r) represents the probability of finding a water at the specified distance during the simulation. Black: λ = 0 (oxidized state); grey: λ = 1 (reduced state). Run 1 data. The peak is produced by W166; it shifts from 6.2 to 7.0 Å on reduction. Lines: mean number N(r) of waters within r of the iron; N(r) is the integral of g(r). The results for midpoint simulations from runs 1 and 2 (with λ = 0.5; both shown as dashed lines) are about midway between the endpoint curves. (B) Similar data for the endpoint simulations of run 3. In this run, the buried water moves towards the protein surface in the oxidized state (λ = 0).