Caldarchaeol is a membrane-spanning lipid

Lipid

Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...

 found in hyperthermophilic

Hyperthermophile

A hyperthermophile is an organism that thrives in extremely hot environments— from 60 degrees C upwards. An optimal temperature for the existence of hyperthermophiles is above 80°C . Hyperthermophiles are a subset of extremophiles, micro-organisms within the domain Archaea, although some bacteria...

 archaea

Archaea

The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...

. Membranes made up of caldarchaeol are more stable since the hydrophobic chains are linked together, allowing the microorganisms to withstand high temperatures. It is also known as dibiphytanyldiglycerol tetraether. Two glycerol

Glycerol

Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

 units are linked together by two strains which consist of two phytane

Phytane

Phytane is a diterpenoid alkane. In contrast to pristane, which is formed from the decarboxylation of phytol, it has one extra carbon.Phytanyl is the corresponding substituent. Phytanyl groups are frequently found in phospholipids in membranes of thermophilic Archaea...

s linked together to form a linear chain of 32 carbon atoms (40 carbons including methyl sidechains).

The configuration of the macrocyclic tetraether has been determined by total synthesis of the C40-diol and comparison with a sample of obtained by degradation of natural tetraether. A synthesis of tertaether has also been carried out.

Additional references

• Focus of research, University of Occupational and Environmental Health, Kitakyushu, Japan
• Langworthy TA, Biochim Biophys Acta 1977, 487, 37
• Monolayer properties of archaeol and caldarchaeol polar lipids of a methanogenic archaebacterium, Methanospirillum hungatei, at the air/water interface. Tomoaia-Cotisel M, Chifu E, Zsako J, Mocanu A, Quinn PJ, Kates M. Chem Phys Lipids. 1992 Nov;63(1-2):131-8
• Ether polar lipids of methanogenic bacteria: structures, comparative aspects, and biosyntheses. Koga Y, Nishihara M, Morii H, Akagawa-Matsushita M. Microbiol Rev. 1993 Mar;57(1):164-82.