Figure 6
Temperature-dependence of disulfide radical lifetimes. The optical density (OD) of an orthorhombic trypsin crystal irradiated for ten beam pulses of 1 s followed over time at 400 (red), 600 (blue) and 750 nm (green) at (a) 100, (b) 130 and (c) 160 K. The decay of the signals at 400 nm after the final pulses was fitted to a first-order exponential to extract disulfide-radical lifetimes. The absorbance at 600 nm corresponds to the presence of trapped electrons; the one at 750 nm is shown as a reference wavelength. The dose per 1 s of beam irradiation was estimated using RADDOSE (Murray et al., 2004) to be 4.4 × 104 Gy, giving a total of 4.4 × 105 Gy for the 10 s of data shown here. |