Figure 4.
X-ray absorption spectroscopy (XAS) indicates the presence of [Fe-S] clusters in EcFeoC. Fe K-edge X-ray absorption fine structure (EXAFS) and Fourier transforms of MBP-EcFeoC (A) and anaerobically reconstituted EcFeoC (B). For ease of interpretation, data are graphed as Fourier transform amplitude versus distance (R) in Å, where 1 Å = 0.1 nm. Black traces represent the experimental data, and red traces represent the simulations. Parameters used to generate the simulated spectra are listed in Table 1. Sample A was in 25 mmol/L Tris buffer, pH 7.5, 200 mmol/L NaCl, 10 mmol/L maltose, 3.6 mol/L ethylene glycol (20% (v/v)), and 0.7 mol/L glycerol (5% (v/v)). Sample B was in 50 mmol/L MOPS buffer, pH 7.5, 150 mmol/L NaCl, 10 mmol/L DTT, and 3.6 mol/L ethylene glycol (20% (v/v)).