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Figure 5 | BMC Evolutionary Biology

Figure 5

From: The globin gene family of the cephalochordate amphioxus: implications for chordate globin evolution

Figure 5

Ligand binding kinetics of recombinantly expressed BflGb4. After photodissociation of CO, the kinetics of ligand rebinding are biphasic, as previously observed for other hexacoordinated globins such as vertebrate Ngb. During the rapid μs phase, CO and the internal ligand (His) compete for the binding to the transient pentacoordinated heme. For the fraction that binds His, there is a slow replacement of His to CO to return to the original stable form. Measurements at different CO concentrations (and several detection wavelengths-not shown) allow a determination of the association rate for both ligands and the dissociation rate of His. The deltaAN on the Y-axis represents the normalized change in absorbance.

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