Structure determination of the phosphatidylglycerosulfate (diether analog) from Halobacterium cutirubrum

A novel phosphosulfolipid has been isolated as the potassium salt from the extremely halophilic bacterium Halobacterium cutirubrum; its molecular formula was established as C46H93PSK2. It accounts for 3–4% by weight of the polar lipids and about 6% of the total lipid phosphorus. The phosphosulfolipid yielded inorganic sulfate and 1-sn-phosphatidyl-3′-sn-glycerol (diphytanyl ether analog) in equimolecular proportions after solvolysis in 0.005 n HCl in tetrahydrofuran, and it was thus a sulfate ester of phosphatidylglycerol. The position of the sulfate group was determined by comparison of the infrared and NMR spectra of the salt and the methyl ester of natural phosphosulfolipid with those of synthetic 1- and 2-sulfate esters of phosphatidylglycerol. The results obtained established the structure of the bacterial phosphosulfolipid as 2,3-di-O-(3′R,7′R,11′R,15′-tetramethylhexadecyl)-sn-glycero-1-phosphoryl-3″-sn-glycero-1″-sulfate.