A general synthesis of glycerophospholipids

The enzymatic synthesis of phosphatidylserine and purification by CM-cellulose column chromatography

Phosphatidylserine has been prepared from phosphatidylcholine by a one-step transphosphatidylation catalyzed by phospholipase D in the presence of L-serine. The resulting mixture of phosphatidylserine and phosphatidic acid is easily and rapidly separated by CM-cellulose column chromatography using step=wise elution with solvents containing increasing percentages of methanol in chloroform. The over-all yield of the procedure is 40-50% depending on the scale of the preparation. CM-Cellulose column chromatography proved to be extremely useful in separating phospholipid mixtures obtained by phosphatidyltransferase reactions of phospholipase D and is also suitable for fractionation of other lipid extracts.

Synthesis of phosphonate and ether analogs of rac-phosphatidyl-L-serine

The chemical synthesis of four phosphonate-containing phosphatidylserine analogs namely, L-serine (+/-)-[2,3-bis(hexadecyloxy) and 2,3-bis(Palmitoyloxy)-propyl] phosphonates, and L-serine (+/-)-[3,4-bis(hexadecyloxy and 3,4-bis(palmitoyloxy)-butyL]phosphonates is descirbed. (+/-)-2,3-Bis(hexadecyloxy) and 2,3-bis(palmitoyloxy)-prophylphosphonic acids and (+/-)-3,4-bis(hexadecyloxy)butylphosponic acid were prepared by reaction of tris(trimethylsily) phosphite on the corresponding haloalkane. Condensation of the above phosphonic acids or (+/-)-3,4-bis(palmitoyloxy)butylphosphonic acid with N-carboxy-L-serine dibenzyl ester in the presence of trichloroacetonitrile or triisopropylbenzenesulfonyl chloride yielded the protected serine intermediates, which on hydrogenolysis gave the desired L-serine analogs. By a similar route, 1,2-dihexadecyl-rac-glycero-3-phosphoric acid was converted to 1,2-dihexadecyl-rac-glycerophospho-L-serine (L-serine (+/-)-2,3-bis(hexadecyloxy)propyl hydrogen phosphate(ester).

An improved synthesis of 1-0-[3H] alkyl-2-acyl-sn-glycerol-3-phosphorylethanolamine with an unsaturated acyl chain

A method is described for the synthesis of 1-0-[9', 10'-(3)H2] octadecyl-2-octadecenoyl-sn-glycerol-3-phosphorylethanol-amine, starting from rac 1-0-octadecen-9'-ylglycerol. The sn-1-alkyl enantiomer is obtained by an enzymatic reaction involving deacylation of rac 1-0-octadecen-9'-yl-2-octadecenoyl-glycerol-3-phosphoryl-N-(tert.-butyloxycarbonyl) ethanolamine with phospholipase A2. The resulting lyso compound is tritiated with 3H2 in the presence of platinum catalyst and reacylated with oleoyl anhydride to yield the final product.

Headgroup conformation and lipid--cholesterol association in phosphatidylcholine vesicles: a 31P(1H) nuclear Overhauser effect study

The nuclear Overhauser effect has been observed in the nuclear magnetic resonance spectra of 31P. The information content of the nuclear Overhauser effect has been applied to the structure and dynamic properties of phosphatidylcholine vesicles. In the vesicles only 1/3 of the theoretical maximum nuclear Overhauser effect enhancement is observed. This result is accounted for by dipolar interactions between the N-methyl protons and the phosphate of phosphatidylcholine, and a correlation time for internal motion of 1.4 X 10(-9) sec. Addition of up to 30% cholesterol does not change the nuclear Overhauser effect enhancement or spin-lattice relaxation time of the vesicles. It is argued that the OH group of cholesterol is hydrogen bonded to the ester carbonyl oxygen of the phosphatidylcholine molecules.

Synthesis and properties of phosphatidyl carnitine and phosphatidyl beta-methylcholine

rac-Phosphatidyl carnitine and rac-phosphatidyl beta-methylcholine were synthesized by direct condensation of phosphatidic acid and the appropriate alcohols in the presence of 2,4,6-triiso-propylbenzenesulphonylchloride and pyridine. Tetraphenylborates of the quarternary ammonium compounds beta-methylcholine and carnitine benzyl ester were shown to be particularly convenient for synthesis in homogeneous phase. Physical and chemical properties of the two phosphoglycerolipids and some intermediates were described. Phosphatidyl carnitine and phosphatidyl beta-methylcholine were hydrolyzed by phospholipase A2 (phosphatide acyl-hydrolase, EC 3.1.1.4), pancreatic lipase (triacylglycerol acyl-hydrolase, EC 3.1.1.3), and phospholipase C from Bacillus cereus (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3). Neither hydrolysis nor transphosphatidylation of phosphatidyl carnitine and phosphatidyl beta-methylcholine was achieved by phospholipase D (phosphatidylcholine phosphatidohydrolase, EC 3.1.4.4). The occurrence of phosphatidyl carnitine in embryonic chicken tissue was suggested by comparison with the synthesized compound. Phosphatidyl carnitine could not be detected in the tissue of rat embryos.