Fig. 6

The crystal structure of BD-FAE. A α-helices are shown in brown and β-sheets in turquoise. Catalytic residues Ser128, Asp237 and His269 are marked in sticks. B In the crystal, the N-terminal tail of one BD-FAE molecule packed against the small β-sheet on the surface of an adjacent BD-FAE molecule in a consecutive manner. C In front view it looks like a tetramer D but in side view it can be seen that the packing formed a fourfold spiral shaped polymer