Howard Goldfine, Professor of Microbiology at the University of Pennsylvania School of Medicine, has authored a new post on Small Things Considered that looks at the interesting evolution of plasmalogens from anaerobes to plant and animal cells.
"Plasmalogens appeared early, but did not survive in aerotolerant and aerobic bacteria. Why not? A clue comes from the finding that the alk-1-enyl ether bond in plasmalogens is broken by reactive oxygen species (ROS) such as superoxide, hydroxyl free radicals, and singlet oxygen. As oxygen increased in the earth’s atmosphere, respiration, with its ability to generate lots more ATP than fermentation, evolved in bacteria. ROS are formed in cells during respiration, typically at the last step in the electron transport chain. This created a problem that aerobes had to solve. The simplest solution was to get rid of plasmalogens and replace them with lipids containing only acyl esters. This process can even be replicated in the laboratory today (see here and here). The separate evolution of Archaea reveals another solution; they make lipids with chemically stable, saturated ether bonds."
Click source for more.