Figure 2. Figure 2. Electron density maps of some representative side-chains at acidic pH: the semi-sharpened (F[o]1/2E[o]1/2 - F[o]1/2E[o]1/2) maps, showing the hydrogen atoms, are represented in cyano and contoured at 1.6 s (s = 0.03 eÅ -3).
