文摘
AHb1 is a hexacoordinated type 1 nonsymbiotic hemoglobin recently discovered in Arabidopsis thaliana. Togain insight into the ligand migration inside the protein, we studied the CO rebinding kinetics of AHb1encapsulated in silica gels, in the presence of glycerol. The CO rebinding kinetics after nanosecond laserflash photolysis exhibits complex ligand migration patterns, consistent with the existence of discrete dockingsites in which ligands can temporarily be stored before rebinding to the heme at different times. This findingmay be of relevance to the physiological NO dioxygenase activity of this protein, which requires sequentialbinding of two substrates, NO and O2, to the heme.