(A) Interactions among four Hap molecules shown in surface (coloured in yellow and by electrostatic surface potential) and cartoon (black and magenta) representations, respectively. (B) Slab view of the packing interface of the Hap–Hap multimer at a cross-section in the primary interaction site of D776–N777. The F1/F2/F3 faces are labelled. The F2 face and F1–F2 edge at the growing ends of the multimer are highlighted in red. Reproduced from Meng et al. 2011 [27] with permission.