title: Structural analysis by reductive cleavage with LiAlH4 of an allyl ether choline-phospholipid, archaetidylcholine, from the hyperthermophilic methanoarchaeon Methanopyrus kandleri.
abstract: A choline-containing phospholipid (PL-4) in Methanopyrus kandleri cells was identified as archaetidylcholine, which has been described by Sprott et al. (1997). The PL-4 consisted of a variety of molecular species differing in hydrocarbon composition. Most of the PL-4 was acid-labile because of its allyl ether bond. The identity of PL-4 was confirmed by thin-layer chromatography followed by positive staining with Dragendorff reagent and fast-atom bombardment-mass spectrometry. A new method of LiAlH4 hydrogenolysis was developed to cleave allyl ether bonds and recover the corresponding hydrocarbons. We confirmed the validity of the LiAlH4 method in a study of the model compound synthetic unsaturated archaetidic acid (2,3-di-O-geranylgeranyl-sn-glycerol-1-phosphate). Saturated ether bonds were not cleaved by the LiAlH4 method. The hydrocarbons formed following LiAlH4 hydrogenolysis of PL-4 were identified by gas-liquid chromatography and mass spectrometry. Four kinds of hydrocarbons with one to four double bonds were detected: 47% of the hydrocarbons had four double bonds; 11% had three double bonds; 14% had two double bonds; 7% had one double bond; and 6% were saturated species. The molecular species composition of PL-4 was also estimated based on acid lability: 77% of the molecular species had two acid-labile hydrocarbons; 11% had one acid-labile and one acid-stable hydrocarbon; and 11% had two acid-stable hydrocarbons. To our knowledge, this is the first report of a specific chemical degradation method for the structural analysis of allyl ether phospholipid in archaea.
authors.affiliation: Department of Chemistry, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Masateru
authors.initials: M
authors.lastname: Nishihara
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Morii
authors.forename: Koji
authors.initials: K
authors.lastname: Matsuno
authors.forename: Mami
authors.initials: M
authors.lastname: Ohga
authors.forename: Karl O
authors.initials: KO
authors.lastname: Stetter
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Koga
mesh_terms: D000498:Allyl Compounds / Q000378:metabolism; D017607:Aluminum Compounds / Q000378:metabolism*; D002794:Choline / Q000378:metabolism*; D004987:Ethers / Q000378:metabolism; D006358:Hot Temperature; D007700:Kinetics; D018020:Lithium Compounds / Q000378:metabolism*; D019640:Methanosarcinales / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D000498:Allyl Compounds; D017607:Aluminum Compounds; D004987:Ethers; D018020:Lithium Compounds; D010743:Phospholipids; C042073:lithium aluminum hydride; D002794:Choline