Nitrogenase Catalytic Cycle — 2D Reaction Wheel

Nitrogenase reduces atmospheric N₂ through a strictly ATP-gated, eight-electron accumulation cycle (the Lowe-Thorneley E0-E8 scheme). This is a native 2D counterpart to the 3D docking-animation simulator: instead of watching one hero complex physically dock and undock, a population of catalytic sites is drawn orbiting a circular reaction-coordinate wheel, each dot's angle encoding exactly how far it has progressed through the same eight-state electron-accumulation cycle, with the same flux-dependent branching between productive N₂ fixation and obligate, wasteful H₂ evolution. A live occupancy histogram and a scrolling NH₃/H₂ production-rate strip chart make the underlying kinetics directly readable as numbers, the way a kinetic biochemist actually studies this system, alongside the same electron-flux, N₂-pressure and irreversible O₂-exposure controls as the 3D version.