Geminate rebinding in R-state hemoglobin: Kinetic and computational evidence for multiple hydrophobic pockets

The time course of CO rebinding to human hemoglobin also exhibits a biphasic geminate rebinding when the protein is entrapped in wet nanoporous silica gel. Potential hydrophobic docking cavities within the alpha and beta chains are identified and the connection between the two xenon sites in the hydrophobic pocket is relatively open, explaining the only slight change in the energetics of ligand migration between the two sites due to decreased protein mobility with viscosity.