Structure of calditol,a new branched-chain nonitol,and of the derived tetraether lipids in thermoacidophile archaebacteria of the Caldariella group

A second category of membrane lipids in extreme thermoacidophile archaebacteria of the Caldariella group is based on the same type of macrocyclic tetraether, incorporating two 16,16′-biphytanyl chains, as those described earlier, but only one of the hydrophilic components is glycerol; the second hydrophilic component is calditol, a unique branched-chain nonitol. It is also shown that in the biphytanyl chains there can be up to 4 cyclopentane rings whose location is demonstrated.