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. 2016 Feb 2;6:20534. doi: 10.1038/srep20534

Figure 4.

Figure 4

(a) Observed and predicted O2-induced 1H longitudinal relaxation enhancements for amide protons against residue number. Difference of longitudinal relaxation rates, ΔR1, for amide protons between 6.4 mM (O2 5 bar) and 0 mM (Ar 2 bar) O2 concentrations. R1 values at each condition are shown in Supplementary Fig. S4 online. Severe line-broadening prohibited quantitative evaluation of ΔR1 for residues 88 and 118 (asterisks). The crystal structure of L99A at 8 atm of xenon pressure possesses three xenon molecules in cavity 4. We added two xenon molecules in cavity 3 and energy minimized. ΔR1 were estimated from 1/r6 weighted distance dependence from each xenon site, using the equation (2). (b) Contributions of each O2-binding site to the predicted 1H longitudinal relaxation enhancements for amide protons. ΔR1 from sites 1–5 were estimated by the following equation: (ΔR1(predict)-f) × (a or b or c or d or e × 105 (1/r1–5)6)/(a × 105 (1/r1)6 + b × 105 (1/r2)6 + c × 105 (1/r3)6 + d × 105 (1/r4)6 + e × 105 (1/r5)6), where r1–5 are distances to each xenon site. The parameters a, b, c, d and e were obtained to be 1.3, 1.1, 1.5, 0.11, 0.10, respectively, by the fitting.