TDXAS study of the conformational landscape of MbCO

We have developed a new experimental approach, Temperature Derivative X-ray Absorption Spectroscopy (TDXAS), to measure the conformational landscape o f a metalloprotein and how it depends on the selected conformational coordi nate of the metal active site structure. We have recorded the temperature v ariation of a selected feature of the X ray Absorption Near Edge Structure (XANES) at the iron K edge of carbonmonoxy-myoglobin (MbCO) of a photoprodu ct and we have extracted the distribution functions g(H) of activation enth alpy barriers H for CO recombination for different conformational coordinat es.