Abstract
1,2-Diacylglyceryl-3-O-carboxyhydroxymethylcholine (DGCC) is a common lipid constituent of Haptophyceae. We have investigated to characterize the biosynthetic pathway of DGCC in Pavlova sp. (Haptophyceae). Feeding experiments using 14C-labeled compounds demonstrated that a precursor of DGCC was choline via ethanolamine, suggesting that the trimethylammonium group of polar group was derived from choline. The polar group of 1,2-diacylglyceryl-O-4'-(N,N,N-trimethyl)homoserine (DGTS), which was present in ferns, mosses and green algae was reported to be synthesized from methionine as C4 backbone. The formation of the trimethylammonium group in DGTS was suggested to be responsible for the three steps of the lipid-linked N-methylation in Rhodobacter sphaeroides. Our results indicated that the biosynthetic pathway of polar group of DGCC was different from that of DGTS. To elucidate the origin of the carboxyl group in polar head group of DGCC, feeding experiments using 13C-labeled compound and the following NMR analysis are now in progress.
