[BBG03-P08] The structure determination of unsaturated archaeol derivatives characteristic for the halophilic archaea lipid-core
Keywords:archaea, halophilic, ether lipid, structure determination
Then, 2 were chemically synthesized according to the reported method and the comparison of the mass spectrum of trimethylsilyl (TMS) ether were presented previously at this meeting. 2 is apparently different from those of Dawson’s unsaturated diether.
About these unsymmetrical diether, 1) the “real” structure of Dawson’s unsaturated archaeol derivative were assumed to the structure 3 or 4 from the intermediate of biosynthesis of tetraether lipid in thermophilic archaea, 2) 5, the resioisomer of 2 about the unsaturated ther bond linked at the glycerol 5 has the possibility of Dawson’s unsaturated diether because of the relation of hydroxyarchaeol in the methanogenic archaea. Then, the chemical synthesis and mass fragmentation analysis of the 4 isomer (2 to 5) was completed.
The comparison and analysis of the mass spectrum of TMS ether was conducterd for the 4 compound. The structure 2 and 5 is different from the “Dawson’s unsaturated diether”. The srtucture 3 and 4 are relatively similar compared with the structure 2 and 5, however, difference of the Dawson’s diether were observed. So, the all of the supoposed four structure were not the real structure. Dawson's unsaturated diether does not have a double bond at the methyl group branching position resulting from the usual isoprenoid biosynthesis (e.g. phytol), probably unsaturation is formed after the saturated isoprenoid formation. Or, it is a a mixture of 3 and 4 (including further double bond isomers).
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