Kinetic analysis by SPR of the PhuS–HemO interaction. PhuS samples injected over Ni-NTA immobilized apo-HemO at 0.5 μM (______), 1.0 μM (…………), 2.5 μM (- - - - -), 5.0 μM (- · - · - · -), 7.5 μM (__ __
__), and 10 μM (____ _
___). (A) Holo-PhuS, (B) Apo-PhuS, (C) Holo-PhuS H209A, (D) Holo-PhuS H210A, (E) Holo-PhuS H212A, and (F) Holo-PhuS H209/210/212A.