Figure 5.

Recombinant UbiV_Pa is a [4Fe-4S] cluster-containing protein. A, UV-visible absorption of metalloproteins UbiV_Pa (dotted line, 32.6 μm) and reconstituted holo-UbiV_Pa (solid line, 22.7 μm). The inset is an enlargement of the 300- to 800-nm region. The molar extinction coefficient, ε₄₁₀, was determined to be 12.95 ± 0.5 mm⁻¹ cm⁻¹ for holo-UbiV_Pa. B, Comparative UV-visible absorption spectra of the WT and different Cys-to-Ala mutants of UbiV_Pa after metal cluster reconstitution. Proteins were analyzed at the following concentrations: 22.7 μm WT, 34.8 μm C39AC180A, and 15.9 μm C193AC197A. Proteins were suspended in buffer containing 50 mm Tris-HCl, 25 mm NaCl, 15% (v/v) glycerol, 1 mm DTT, pH 8.5.