Ethers phytanyl

Ether-linked lipids constitute up to 35% of the total phospholipid in molluscs. Although they are usually regarded as animal constituents, small amounts of ether-linked lipids have been identified in plants. The major phospholipids of archaebacterial membranes are ether-linked derivatives of the polyprenyl phytanyl group and of the dimeric biphytanyl group (Chapter... 

In addition to the previously mentioned phytanyl ether phospholipids, methanogens contain diphytanyl tetraether lipids that are both glycerophospholipids and glycolipids. 

These archael membrane lipids consist of monopolar ether head groups and saturated, branched phytanyl chains which are... 

Kates M (1978) The phytanyl ether-linked polar lipids and isoprenoid neutral lipids of... 

Fig. 2.15 (a) Examples oflipids in the membranes and cell walls of eubacteria. (b) Phytanyl ether lipids in archaebacterial cell membranes. 

The diacylglycerol backbone in eubacteria and eukaryotes is sn-3-glycerol esterified at positions 1 and 2 with long-chain fatty acids (Fig. 2). In archaebacteria (Fig. 3), the opposite isomer sn-1-glycerol forms the lipid backbone and the hydrophobic domain is composed of phytanyl (saturated isoprenyl) groups in ether linkage at positions 2 and 3 (an archaeol)... 

Archaea are a group of organisms, previously classified as bacteria, from which eubacte-ria and other life may have evolved. A melavonic acid (six carbon)-building block is used for synthesis instead of acetic acid. The generated phytanyl chains are attached to glycerol moieties of complex lipids by ether linkages. Thus, these lipids are unlike anything found in eubacteria or eukaryotes today. 

Fig. 11. Membrane lipids. Structure of the phyta-nyl ether membrane lipids of Archaebacteria. Sometimes the ends of the phytanyl residues of a particular molecule are linked to each other or to those of an equivalent molecule in the other monolayer of the lipid bilayer of the biomembrane.

Phytanyl residues bound by an ether bridge to glycerol (or to the polyol calditol) are important constituents of the ether lipids of archaebacteria membranes. In addition dimeric compounds occur in which two phytanyl residues are interlinked tail-to-tail . The phytanyl moieties may be desaturated and contain one to four cyclopentane rings (Fig. 113). 

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