We demonstrate the first application of L-edge X-ray absorption spectroscopy (XAS) to the electronic characterization of biological photolysis products. The experimental L-edge XAS spectra of deoxymyoglobin (deoxy Mb), oxymyoglobin (MbO 2 ), carbonmonoxymyoglobin (MbCO), and the low-temperature photoproducts (Mb*CO and Mb*O 2 ) are presented and compared to simulated spectra using a ligand field multiplet calculation. This analysis indicates that MbCO and MbO 2 are both low spin and does not support some previous studies which suggest that MbO 2 has an intermediate spin. Both photoproducts, Mb*CO and Mb*O 2, are different from deoxy Mb in the Fe II electronic structure. In addition, different low-temperature photolysis intermediates are suggested for MbCO and MbO 2 . The L-edge XAS spectra for Fe III in aquometmyoglobin (met Mb) and azidomet myoglobin (MbN 3 ) provide a comparison of the ferrous versus ferric myoglobin species. Finally, the special advantages of using soft X-ray absorption spectroscopy for understanding the electronic transitions coupled to photolysis-induced structural changes are discussed.
No takes yet. Share an insight, caveat, or question.
Wang et al. (1997) studied this question.