Figure 2.

Cryo-EM structure of an active, asymmetric RNR α₂β₂ complex (α₂, blue and green; β₂, orange and red). A Asymmetric structure of the overall complex showing an ordered α(green)/β(orange) pair and a partially disordered α′(blue)/β′(red) pair where the displaced α′/ β′ pair has already turned over, and the ordered α/β is poised for radical transfer. B Radical transfer pathway residues with distances in Å in the α/β pair. C Proposed pathway for H⁺ escape following Y₃₅₆[β] (Y₇₃₁[α]) oxidation involving several ionizable residues and potentially ordered waters (red blurred circles) from crystallographic structures.