The conformational change in Nm23-H1 under oxidative conditions occurs sequentially from left to right. (a) Superposition of a native hexamer form that has NDPK activity (colored beige). (Bottom box) The monomer form of Nm23-H1 showing key residues and domains related to oxidative conformational changes. Spheres colored yellow are sulfurs on Cys4 and Cys145, and magenta is sulfur on Cys109. The carbons of these cysteines are tan, red, and blue, respectively. Spheres colored cyan are atoms in the active site (His118). (b) Superposition of the oxidized hexameric form that has no NDPK activity (left, colored green) dissociates into dimers (right). The C-terminal-interacting region of the Kpn loop (aa 109–114) region is shown in blue, the C-terminal domain (aa 140–151) is shown in red, the sulfurs on Cys4 and Cys145 are yellow balls and those on the Cys109 residues are magenta balls. The carbons in those residues Cys4, Cys109, and Cys145 are green, blue, and red balls, respectively.