Figure 1.

Overall crystal structures of ultralong Fabs D08 (a), D08* (b) and BLV5B8* (c), presented in cartoon representation with a semi-transparent surface overlay. Representative electron density is contoured in 1.0σ units and illustrated with mesh notation for the tryptophan at the core of the VL domain (d, e, f), the core of the knob mini-domain of Fabs D08 (g) and D08* (h) or the β-stalks of the ultralong loop stalk motif of BLV5B8* (i). The D08 heavy chain is coloured black and the D08 light chain is coloured red, while the BLV5B8 heavy chain is coloured white and the light chain is coloured magenta.