Fig. 1.

Lipid structures and anammox metabolism. (A) Representative straight-chain PCs. Nomenclature: x:y is a straight chain with x carbons and y degrees of unsaturation. (B and C) Ladderane lipids such as [3][3]PC and [5][3]PC occur in the anammoxosome membrane of anammox bacteria. (B) [3][3]PC and [5][3]PC phospholipids and unnatural analog [5][5]PC that have been prepared by enantioselective chemical synthesis. (C) Anammox catabolism is believed to provide energy to the cell by oxidizing the toxic intermediate hydrazine (N₂H₄). Hydrazine oxidation is thought to be coupled to proton influx, generating a pH gradient that drives ATP synthesis. Standard reduction potentials, E₀′, for redox half reactions are shown.