Occupancy of the gas binding sites by xenon and nitrous oxide as a function of pressure. (A) Urate oxidase, UOX-I, (B) lysozyme, LYSO-I, (C) myoglobin, MB-I, (D) myoglobin, MB-II, (E) myoglobin, MB-III, (F) myoglobin, MB-IV, (G) myoglobin, MB-V, (H) neuroglobin, NGB-II, (I) neuroglobin, NGB-III, and (J) neuroglobin, NGB-IV. Statistical analysis showed a significant difference between xenon and nitrous oxide occupancy of UOX-I, LYSO-I, MB-II, MB-III, MB-V, NGB-II, NGB-III, and NGB-IV, but not between xenon and nitrous oxide occupancy of MB-I and MB-IV. Orange lines: xenon (Xe); blue lines: nitrous oxide (N₂O). UOX-I: binding site no. 1 in urate oxidase; LYSO-I: binding site no. 1 in lysozyme; MB-I, MB-II, MB-III, MB-IV, and MB-V: binding sites nos. 1 to 5 in myoglobin; NGB-II, NGB-III, and NGB-IV: binding sites nos. 2 to 4 in neuroglobin. Y-axis: occupancy of the gas binding sites by xenon and nitrous oxide as expressed in %; X-axis: pressure of gas expressed in bar (1 bar = 0.1 MPa).