Affinity of small ligands to myoglobin studied by the 3D-RISM theory

It is found that NO, CO, and H2S show greater affinity to the Xe sites than O2 does, while the affinity of Xe is lower than that of O2. A relevance of the results to the physiological activity of the protein is speculated. The physical origin of the difference in affinity among the ligands is discussed.