Direct Electrochemistry of Tetraheme Cytochrome c554 from Nitrosomonas europaea: Redox Cooperativity and Gating.

The article focuses on the protein film voltammetry (PFV) of the tetraheme cytochrome c554 (cyt c554) from Nitrosomonas europaea. Cyt c554 is the natural redox partner of the enzyme hydroxylamine oxidoreductase (HAO), which oxidizes hydroxylamine to nitrite. The study examines the redox reactions of cyt c554. The authors find evidence for previously unobserved cooperativity and redox directionality.