Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2051555 | FEBS Letters | 2007 | 7 Pages |
Abstract
Here we report the results of transient absorption and photoacoustic calorimetry studies of CO photodissociation from the heme domain of the bacterial oxygen sensor HemAT-Bs. The results indicate that CO photolysis is accompanied by an overall ÎH of â19 kcal molâ1 and ÎV of +4 ml molâ1 as well as a red-shifted kinetic difference spectrum all occurring in <50 ns. Analysis of the ÎH/ÎV reveals that a conformational change takes place with a ÎHconf of â40 kcal molâ1 and ÎVconf of â22 ml molâ1. These thermodynamic changes are consistent with an increase in the solvent accessible surface area of the protein upon ligand dissociation, as observed in the X-ray structure of the ferric CN-bound and CN free forms of HemAT-Bs.
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Authors
Audrey Mokdad, Mark Nissen, James D. Satterlee, Randy W. Larsen,