Heptose-containing pentaglycosyl diglyceride among the lipids of Acholeplasma modicum.

A pentaglycosyl diglyceride with the tentative structure of galactosyl-galactosyl-mannoheptosyl-glucosyl-glucosyl diglyceride was found to be the major glycolipid in Acholeplasma modicum. The heptose is d-glycero-d-mannoheputose. The diglyceride-terminating moiety possesses the structure O-alpha-d-glucopyranosyl-(1 --> 2)-O-alpha-d-glucopyranosyl-sn-1,2-diglyceride. Other glycolipids occurring in this organism are a diglucosyl diglyceride and a monoglucosyl diglyceride with structures identical to the terminal segments of the pentaglycosyl diglyceride. More fully acylated derivatives of these two glycolipids also occur. The phospholipids are all of the glycerophosphoryl type. The neutral lipids are composed of diglycerides and four polyterpenes. The polyterpenes consist of both colored and colorless carotenoids and become radiolabeled with both [(14)C]acetate and [(14)C]mevalonate.