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Fig. 1 | BMC Biology

Fig. 1

From: The structure of a prophenoloxidase (PPO) from Anopheles gambiae provides new insights into the mechanism of PPO activation

Fig. 1

Crystal structure of A. gambiae PPO8. (a) Overall structure of the homodimer with each subunit shown in cyan and green, respectively. Cu atoms are shown as brown spheres. (b) The domain structure of AgPPO8: pro-region, magenta; domain I, blue; domain II, yellow; domain III, green. The Cu atoms are shown as brown spheres and the disulfide bonds are shown as red sticks. The side chain of Arg51 preceding the proteolytic cleavage site is shown as a black stick. (c) Superposition of AgPPO8 (cyan) with M. sexta PPO heterodimer (PPO-1 in magenta and 2 in yellow, PDB ID 3HHS). AgPPO8 is 41.1 % identical in a.a. sequence to MsPPO1 and 38.8 % to MsPPO2. (d) The di-copper active site of A. gambiae PPO8. The Cu atoms are shown as brown spheres. Six conserved His residues (magenta) coordinate CuA and CuB, and are stabilized by three Phe residues (F248, F415 and the 'placeholder' F99, shown as red sticks). V406 (orange) aligns to a putative catalytic residue E395 in MsPPO2. Glu364 (green) forms a salt bridge (black dash) with R244 (yellow), and is required for the enzymatic activities of AgPPO8. The secondary structures of AgPPO8 are shown and colored in cyan

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