Insights into redox partner interactions and substrate binding in nitrite reductase from alcaligenes xylosoxidans: Crystal structures of the Trp138His and His313Gln mutants

Biochemical and structural results on two key mutants, one postulated to be important for the interaction with the partner protein and the other for substrate entry is presented. Trp138, adjacent to one type of the type-1 Cu ligands, is one of the residues surrounding a small depression speculated to be important in complex formation with the physiological redox partners, azurin I and II.