Fig. 10.

Hypothetical pathway from polyprenyl pyphosphates to archaeal lipids and mechanism for the formation of a glyceryl head-group. In the transition state for the reaction of polyprenyl pyrophosphate and glyceryl phosphate, the carbocation intermediate at C1-C3 carbons of polyprenyl pyrophosphate is formed and the negative charge developed on pyrophosphate group is stabilized by coordination with Mg ²⁺. The pyrophosphate complexed with Mg ²⁺ could serve as a good leaving group. PPA polyphosphoric acid