Photothermal studies of CO photodissociation from mixed valence Escherichia coli cytochrome bo3
- Mikšovská, Jaroslava
- Gennis, Robert B.
- Larsen, Randy W.
DOIAbstract
AbstractHere, we report the volume and enthalpy changes accompanying CO photodissociation from the mixed valence form of cytochrome bo3 oxidase from Escherichia coli. The results of photoacoustic calorimetry indicate two kinetic phases with distinct volume and enthalpy changes accompanying CO photodissociation from heme o3 and its transfer to CuB. The first phase occurring on a timescale of <50ns is characterized by a volume decrease of −1.3±0.3mLmol−1 and enthalpy change of 32±1.6kcalmol−1. Subsequently, a volume increase of 2.9mLmol−1 with an enthalpy change of −5.3±2.5kcalmol−1 is observed with the lifetime of ∼250ns (this phase has not been detected in previous optical studies). These volume and enthalpy changes differ from the volume a...
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