Table 1.

Affinities of EcoFepA and KpnFepA0027 for ferric catecholates

¹ K_d values were calculated by the one-site (with background) equation of Grafit 6.02.

² Bacteria were grown in iron-deficient minimal MOPS medium to 5 × 10⁸ cells/ml. For fluorescence studies, they were modified with FM and washed with and resuspended in PBS.

³ Binding determinations were conducted in a 10 ml volume in an Olis Clarity spectrofluorometer by adding varying concentrations of purified FeEnt or FeGEnt to bacteria at 1.25 × 10⁷ cells/ml and observing quenching. The excitation/emission maxima were 488/520 nm.

⁴ [⁵⁹Fe]Ent binding determinations were conducted in 10 ml of ice-cold PBS (26), with cells chilled on ice.