PHOSPHOLIPID METABOLISM IN SUBACUTE SCLEROSING PANENCEPHALITIS : ACTIVITY OF BRAIN PHOSPHOLIPASE A2 TOWARDS SPECIFICALLY LABELLED 1,2-DIACYL-, 1-ALK-1''-ENYL-2-ACYL- AND 1-ALKYL-2-ACYL-sn-GLYCERO-3-PHOSPHORYLCHOLINE

—1,2-Diacyl-, 1-alk-1′-eny1-2-acyl- and 1-alky1-2-acyl-sn-glycero-3-phosphorylcholine specifically labelled with different fatty acids at the 2 position, were prepared enzymically using the acyltransferase system of rabbit sarcoplasmic reticulum. The substrates were submitted to hydrolysis by phospholipase A₂ (phospholipid acyl-hydrolase, EC 3.1.1.4) obtained from normal and brain tissue affected with subacute sclerosing panencephalitis. In the diseased tissue an increase of phospholipase A₂ activity ranging from 46 to 54% could be observed in comparison to the control brain for all substrates investigated. Among the investigated substrates phospholipase A₂ had the highest affinity for the 1,2-diacylcompound, whereas alkenylacyl- and alkylacyl-sn-glycero-3-phosphorylcholine were cleaved at almost similar rates. The hydrolysis rate of choline-plasmalogen and the corresponding diacyl compound by the enzyme was greatly influenced by the fatty acid moiety located at the 2 position of the substrates.     

Continuous fluorometric assay of phospholipase A2 with pyrene-labeled lecithin as a substrate

1,2-Bis[4-(1-pyreno)butanoyl]-sn-glycero-3-phosphorylcholine was synthesized as a fluorogenic substrate for phospholipase A₂. It has a critical micellar concentration of 7.3 μm and gives only excimer fluorescent emission at 480 nm in aqueous micellar dispersion. When hydrolyzed by phospholipase A₂, the products give only monomer emission which is monitored best at 382 and 400 nm. Conditions were developed for an assay for phospholipase A₂ using this substrate. The assay was sensitive to as little as 8 ng of pure porcine pancreatic phospholipase A₂.     

Phospholipases of Leptospira. I. Presence of phospholipase A1 and lysophospholipase in Leptospira biflexa

The hydrolysis of phosphatidylethanolamine, phosphatidylcholine, lysophosphatidylcholine, and trioleoylglycerol by Leptospira biflexa strain Urawa was studied in vitro. Phospholipase A₁ was identified by the formation of ³²P- and ¹⁴C-labeled lyso-derivatives from ³²P-phosphatidylcholine, ³²P-phosphatidylethanolamine, or 1-acyl-2-[1-¹⁴C]oleoyl-sn-glycero-3-phosphorylcholine. Phospholipase A₁ activity was independent of lipase in the microorganism since ¹⁴C-labeled trioleoylglycerol was scarcely attacked under the same conditions in which the phospholipids were hydrolyzed. Lysophospholipase activity was also demonstrated using ³²P- and non-labeled lysophosphatidylcholine. The activity of phospholipase A₁ was found in a broad range of pH but no optimal pH was determined. The pH optimum of lysophospholipase was 8.0. Both enzymes were labile to heat. Phospholipase C activity, however, could not be detected because no radioactive di- and monoacylglycerol was found in the experiment with 1-acyl-2-[1-¹⁴C]-oleoyl-sn-glycero-3-phosphorylcholine as the substrate. It was inferred that phosphatidylethanolamine, which was the major component of phospholipids in leptospirae, was hydrolyzed serially by phospholipase A (A₁ and/or A₂?) and lysophospholipase to glycerophosphorylethanolamine via 2-acyl-type-lyso-derivative as one metabolic pathway of the substrate.     

Discrimination between the regioisomeric 1,2- and 1,3-diacylglycerophosphocholines by phospholipases

The artificial 1,3-diacyl-glycero-2-phosphocholines (1,3-PCs), which form similar aggregate structures as the naturally occurring 1,2-diacyl-sn-glycero-3-phosphocholines (1,2-PCs), were tested as substrates for different classes of phospholipases such as phospholipase A₂ (PLA₂) from porcine pancreas, bee and snake venom, and Arabidopsis thaliana, phospholipase C (PLC) from Bacillus cereus, and phospholipase D (PLD) from cabbage and Streptomyces species. The regioisomers of the natural phospholipids were shown to bind to all investigated phospholipases with an affinity similar to the corresponding naturally occurring phospholipids, however their hydrolysis was reduced to different degrees (PLA₂s and PLC) or even abolished (PLDs belonging to the PLD superfamily). The results are in accordance with binding models obtained by docking the substrates to the crystal structures or homology models of the phospholipases.     

Purification of apo-3-D-(-) hydroxybutyrate dehydrogenase from rat liver mitochondria

Summary 3-D-(-) hydroxybutyrate dehydrogenase (EC 1.1.1.30) from rat-liver mitochondria was purified in the form of the soluble, phospholipid-free apoenzyme by a procedure involving: (1) solubilization of the membrane bound enzyme by controlled digestion of membrane phospholipids with porcine pancreas phospholipase A₂; (2) stabilization and separation of the released apoenzyme as a complex with egg-lecithin by gel filtration on Sephadex G-100; and (3) specific displacement of the apoenzyme from the enzyme-lecithin complex by treatment withBothrops atrox venom phospholipase A₂ (in the absence of Ca²⁺ ions) and subsequent separation of the displaced apoenzyme by gel filtration on Sephadex G-100. The method described is adequate for samples containing about 40 mg of mitochondrial protein. The yield in activity is 42% of that present in mitochondria and the degree of purification of the apodehydrogenase is about 170 fold. The purified apodehydrogenase shows one single sharp band when submitted to SDS polyacrylamide gel electrophoresis, with a mobility corresponding to a molecular weight of 38000 daltons. Gel filtration of the apoenzyme on Sephadex G-100 shows two active peaks with molecular weights of 76000 and 38500 daltons, indicating two different states of aggregation, namely, monomer and dimer. The corresponding diffusion coefficients are 7.73 (monomer) and 5.70 (dimer) × 10^–7. The apodehydrogenase preparation is devoid of phospholipids and is catalytically inactive. It can be reactivated by addition of egg lecithin or phospholipid mixtures containing lecithin in a suitable physical state. Reactivation occurs after formation of an active apodehydrogenase phospholipid complex.Abbreviations HBD 3-D-(-) hydroxybutyrate dehydrogenase - apoHBD 3-D-(-) hydroxybutyrate dehydrogenase apoenzyme - SMP submitochondrial particles - DFP diisopropylfluorophosphate - BSA bovine serum albumin - MPL mitochondrial phospholipids - L-diC₁₄ 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine - lysoC₁₄ 1-myristoyl-sn, glycero-3-phosphorylcholine - D-diC₁₀ 2.3-didecanoyl-sn-glycero-1-phosphorylcholine - tlc thin layer chromatography - SDS sodium dodecylsulfate Dedicated to ProfessorLuis F. Leloir on the occasion of his 70th birthday.     

Dynamics of formation of lysoforms on enzymatic hydrolysis of phosphatidylalkanols

Hydrolysis of 1,2-dioleoyl-sn-glycero-3-phosphomethanol (DOPM), 1,2-dioleoyl-sn-glycero-3-phosphoethanol (DOPEt), 1,2-dioleoyl-sn-glycero-3-phosphoethyleneglycol (DOPEG), and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) catalyzed by phospholipase A₂ (PLA₂) from porcine pancreas was studied in single-component and binary model bilayer membranes (liposomes). The presence of anionic phosphatidylalkanols increases the rate of hydrolysis of zwitterionic DOPC in liposomes by the action of PLA₂. The rate of formation of lysoforms of anionic (acidic) lipids at the initial reaction stage in single-component liposomes increased in the following sequence: DOPEG < DOPM < DOPEt (compared with that for the zwitterionic DOPC). In binary liposomes formation of lyso-DOPC increased in the presence of acidic lipids in the following sequence: DOPM < DOPEt < DOPEG. This indicates that the size of polar fragment of the second substrate and the presence of free hydroxy groups in the head of DOPEG may possibly activate DOPC hydrolysis by the action of PLA₂ in the presence of anionic phospholipids including cardiolipin; the studied phospholipids model fragments of the latter.     

Phospholipase A2 from Trypanosoma brucei gambiense and Trypanosoma brucei brucei: Inhibition by Organotins

Activity and kinetics of phospholipase A₂ (PLA₂) from Trypanosoma brucei gambiense (Wellcome strain) and Trypanosoma brucei brucei (GUTat 3.1) were examined using two different fluorescent substrates. The activity in the supernatants of sonicated parasites was Ca²⁺-independent, strongly stimulated by Triton X-100 with optimum activity at 37°C and pH 6.5–8.5. To encourage a possible interaction between the parasite enzyme and organotin compounds, fatty acid derivatives of dibutyltin dichloride were synthesized and evaluated as potential inhibitors of PLA₂. The enzyme from the two-trypanosome species differ with respect to kinetic parameters and are noncompetitively inhibited by the organotin compounds. The Michaelis constant (K_M) for PLA₂ from T. b. brucei is 63.87 and 30.90 μM while for T. b. gambiense it is 119.64 and 32.90 μM for the substrates l,2-bis-(1-pyrenebutanoyl-sn-glycero-3-phosphocholine (PBGPC) and 2-(12-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dode-canoyl-1-hexadecanoyl-sn-glycero-3-phosphocholine (NBDC₁₂-HPC), respectively.     

Partitioning of Tetrachlorophenol into Lipid Bilayers and Sarcoplasmic Reticulum: Effect of Length of Acyl Chains,Carbonyl Group of Lipids and Biomembrane Structure

We report results of a partitioning study of 2,3,4,6-tetrachlorophenol (TeCP). In the study we explored (1) the effect of the length of acyl chains of lipids (C16:1 – C24:1) and alkanes (C6–C16), (2) the role of the carbonyl group of lipids, and (3) the effect of molecular structure of the sarcoplasmic reticulum membrane on TeCP partitioning. Mole fraction partition coefficients have been measured using equilibrium dialysis for un-ionized (HA), and ionized (A) species, Kp_x^HA, Kp_x^A. Their values are concentration-dependent. Partition coefficients were analyzed in terms of a model that accounts for saturation of membrane associated with the finite area of partition site, and electrostatic interactions of (A-) species with charged membrane. Limiting values of partition coefficients, corresponding to infinite dilution of solute, Kp_x0^HA, Kp_x0^A were obtained. Kp_x0^HA and Kp_x0^A measure the strength of solute-membrane interactions. Studies were done with single-layered vesicles of lipids with variable chain length: 1,2-dipalmitoleoyl-sn-glycero-3-phosphocholine (C16:1), 1,2-dioleoyl-sn-glycero-3-phosphocholine (C18:1), 1,2-dierucoyl-sn-glycero-3-phosphocholine (C22:1), and 1 ,2-dinervonoyl-sn-glycero-3-phosphocholine (C24:1), and egg-PC. Kp_x0 for transfer of TeCP from water into lipid membranes was found to be independent of the length of acyl chains, whereas Kp_x0 for transfer from water into alkanes increased with the length of alkane. The effect of the carbonyl CO group of lipids on partitioning was measured using 1,2-di-o-octadecenyl-sn-glycero-3-phosphocholine (CO absent) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (CO present) liposomes. Carbonyl groups, known to change dipolar potential, had no effect on partitioning. Partition coefficients of un-ionized and ionized forms of TeCP were invariant to the presence of proteins and other membrane components of sarcoplasmic reticulum (SR) membrane.     

PHOSPHOLIPID METABOLISM IN EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS: ACTIVITY OF BRAIN PHOSPHOLIPASE A1, TOWARDS SPECIFICALLY LABELLED GLYCEROPHOSPHOLIPIDS

—The activity of phospholipase A₁ (phosphatide acylhydrolase, EC 3.1.1.4) was measured against phosphatidylcholine, -ethanolamine and -serine, specifically labelled with different fatty acids at either the 1 or 2 position, during experimental allergic encephalomyelitis in rats. In the acute stage of the disease there was a significant increase in enzyme activity in comparison to that from the control animals. The enhanced phospholipase A₁ activity was of the-same order of magnitude for all 1,2-diacyl-glycerophospholipids investigated. The phospholipase A₁-catalysed release of labelled fatty acids from molecular species of phosphatidylcholine decreased slightly with increasing degree of unsaturation of the fatty acids at the 1-position. The K_m-values of the highly purified enzyme were not altered by the demyelinating disorder. The phospholipase A₁ activity returned to the control level in the recovery stage.     

THE METABOLISM OF [1-14C]ARACHIDONIC ACID IN THE NEUTRAL GLYCERIDES AND PHOSPHOGLYCERIDES OF MOUSE BRAIN1

Abstract— [1-¹⁴C]Arachidonic acid was incorporated into brain lipids with a half-life of approx. 5 min. Within 40 min after intra-cerebral injection, radioactivity was distributed mainly among the diacyl-sn-glycero-3-phosphorylcholine (45 per cent), diacyl-sn-glycero-3-phosphorylinositol (22 per cent), diacyl-sn-glycero-3-phosphorylethanolamine (14 per cent) and triacylglycerols (9 per cent). At comparable times, the proportions of radioactivity distributed in diacyl-sn-glycero-3-phosphorylserines and alkenylacyl-sn-glycero-3-phosphorylethanolamines were relatively small. Radioactivity was initially incorporated into the phosphatidio acids and diacylglycerols before labelling of the triacylglycerols and other phosphogly-cerides. The relative specific activity of diacylglycerols was maximum between 3–6 min after injection. Due to the small level of diacyl-sn-3-phosphorylinositol present in brain, its relative specific radioactivity was higher than other types of brain phosphoglycerides. Results of the experiment thus indicate that labelled arachidonic acid is an excellent precursor for metabolic studies with regard to acyl groups present in the 2-position of the phosphoglyceride molecules. Furthermore, this labelled precursor is specially useful in studies related to metabolism of diacyl-sn-glycero-3-phosphorylinositol in brain.     

Hydrolysis of 1-palmitoyl-2-[6-(pyren-1-yl)]hexanoyl-sn-glycero-3-phospholipids by phospholipase A2: effect of the polar head-group

The effect of the phospholipid polar head-group on the porcine pancreatic phospholipase A₂ (phosphatidylcholine 2-acylhydrolase, EC 3.1.1.4) reaction was studied using 1-palmitoyl-2-[6-(pyren-1-yl)]hexanoyl-sn-glycero-3-phosphatidylcholine,-ethanolamine, -glycerol, -monomethylester and -serine as substrates. Except for the monomethylester analogue, which was maximally activated by 3.5 mM CaCl₂, maximal enhancement of hydrolysis of the other pyrenephospholipids was obtained at 2 mM Ca₂₊. Sodium cholate inhibited hydrolysis of the ethanolamine and serine lipids, whereas a slight (1.4–2.0-fold) activation was observed for the -choline, -glycerol and -monomethylester derivatives. Arrhenius plots of hydrolysis of pyrenephospholipids by porcine pancreatic phospholipase A₂ revealed no discontinuities, thus indicating the absence of phase transition for these lipids in the temperature range 15–45°C. Specific activities of porcine and bovine pancreatic, porcine intestinal and snake venom (Crotalus atrox) phospholipases A₂ towards pyrenephospholipid liposomes were then compared. Whereas the snake venom phospholipase A₂ preferred phosphatidylcholine as a substrate, the other phospholipases A₂ preferred acidic phospholipids in the order monomethylester ⩾ glycerol ⩾ serine.     

Increased phospholipase a activity and formation of communicative contacts between Acanthamoeba castellanii cells : Effect of 3′,5′-Cyclic AMP

1. 1. Exogenous 1-palmitoyl-sn-glycero-3-phosphorylcholine becomes incorporated into the membrane of A. castellanii within 2 min of incubation.

2. 2. Homogenates of A. castellanii are shown to contain phospholipase A activity.

3. 3. The phospholipase A activity is dependent on the population density of the culture.

4. 4. An increased phospholipase A activity in older cultures of A. castellanii, due to an increased population density, induces aggregation of these cells in a way that communicative contacts are formed.

5. 5. At pH 5.5, the pH value at which the cells were grown, the phospholipase A activity is stimulated by cAMP; at pH 8.0 no stimulation occurs.

     

Simple and rapid screening methods for microorganisms with phospholipase A1, A2 and C activities

Summary A simple and rapid screening method for microorganisms with phospholipase A₁, A₂ and C activities using agar plate and gas chromatography (GC) method was successfully carried out. In agar plate method, soy bean lecithin and taurocholic acid were used as carbon source and emulsifier, respectively. In this agar plate method, microorganisms with phospholipase A₁ and A₂ or C activity produce a halo around the colony and two kinds(A's and C) of microorganisms are clearly distinguished by turbidity of the halo. Microorganisms with phospholipase A₁ and A₂ activity is simply distinguished by GC using a synthetic phospholipid containing different fatty acid at sn-1 and sn-2 position.     

Characterization of the transacylase activity of rat liver 60-kDa lysophospholipase-transacylase. Acyl transfer from the sn-2 to the sn-1 position

Rat liver 60-kDa lysophospholipase-transacylase catalyzes not only the hydrolysis of 1-acyl-sn-glycero-3-phosphocholine, but also the transfer of its acyl chain to a second molecule of 1-acyl-sn-glycero-3-phosphocholine to form phosphatidylcholine (H. Sugimoto, S. Yamashita, J. Biol. Chem. 269 (1994) 6252–6258). Here we report the detailed characterization of the transacylase activity of the enzyme. The enzyme mediated three types of acyl transfer between donor and acceptor lipids, transferring acyl residues from: (1) the sn-1 to -1(3); (2) sn-1 to -2; and (3) sn-2 to -1 positions. In the sn-1 to -1(3) transfer, the sn-1 acyl residue of 1-acyl-sn-glycero-3-phosphocholine was transferred to the sn-1(3) positions of glycerol and 2-acyl-sn-glycerol, producing 1(3)-acyl-sn-glycerol and 1,2-diacyl-sn-glycerol, respectively. In the sn-1 to -2 transfer, the sn-1 acyl residue of 1-acyl-sn-glycero-3-phosphocholine was transferred to not only the sn-2 positions of 1-acyl-sn-glycero-3-phosphocholine, but also 1-acyl-sn-glycero-3-phosphoethanolamine, producing phosphatidylcholine and phosphatidylethanolamine, respectively. 1-Acyl-sn-glycero-3-phospho-myo-inositol and 1-acyl-sn-glycero-3-phosphoserine were much less effectively transacylated by the enzyme. In the sn-2 to -1 transfer, the sn-2 acyl residue of 2-acyl-sn-glycero-3-phosphocholine was transferred to the sn-1 position of 2-acyl-sn-glycero-3-phosphocholine and 2-acyl-sn-glycero-3-phosphoethanolamine, producing phosphatidylcholine and phosphatidylethanolamine, respectively. Consistently, the enzyme hydrolyzed the sn-2 acyl residue from 2-acyl-sn-glycero-3-phosphocholine. By the sn-2 to -1 transfer activity, arachidonic acid was transferred from the sn-2 position of donor lipids to the sn-1 position of acceptor lipids, thus producing 1-arachidonoyl phosphatidylcholine. When 2-arachidonoyl-sn-glycero-3-phosphocholine was used as the sole substrate, diarachidonoyl phosphatidylcholine was synthesized at a rate of 0.23 μmol/min/mg protein. Thus, 60-kDa lysophospholipase-transacylase may play a role in the synthesis of 1-arachidonoyl phosphatidylcholine needed for important cell functions, such as anandamide synthesis.     

The turnover of phosphoglycerides in the subcellular fractions of mouse brain: a study using (1-14C)oleic acid as precursor

Abstract— The turnover of phosphoglycerides in subcellular fractions of adult mouse brain was examined after intracerebral injection of [1-¹⁴C]oleic acid. Radioactivity of the total brain homogenate decreased rapidly thereafter, with only 4 per cent of the radioactivity remaining at the end of 3 months. The rate of decrease of radioactivity in the subcellular fractions was in the order: cytosol, microsomes, synaptosomes and myelin. Increasing amounts of radioactivity were detected in the alkenyl groups and cerebrosides, but metabolic conversions were not as extensive as found previously with the palmitoyl group. The specific radioactivities for diacyl sn-glycero-3-phosphorylcholine and diacyl sn-glycero-3-phosphorylethanolamine were highest in the microsomal fraction and decreased with time. The apparent half-lives for the diacyl sn-glycero-3-phosphorylcholine and the diacyl sn-glycero-3-phosphorylethanolamine in the microsome and synaptosome-rich fractions were 1-3.5 days when estimated between 1 and 7 days after injection. The rate of decay for the brain membrane phosphoglycerides was not linear with time, probably because of the extensive amount of recycling occurring within the system. Radioactivity was incorporated into the phosphoglycerides of the myelin but equilibration of radioactivity between microsomes and myelin required 7–14 days.     

Enzymatic deacylation of l,2-diacyl-sn-glycero-3-phosphocholines to sn-glycerol-3-phosphocholine

This research was undertaken to study the enzymatic deacylation of l,2-diacyl-sn-glycero-3-phosphocholines (sn-1,2-PC) to sn-glycerol-3-phosphocholine (GPC); this compound could be an useful intermediate in the synthesis of “structured” sn-1,2-PC, after re-acylations of the two sn-positions of the glycerol backbone. The enzymatic reactions represent a valid alternative to the chemical deacylation that can be simply obtained in alkaline conditions. High conversion were achieved using a lipase selective for the sn-1-position of sn-1,2-PC (Lipozyme IM, from Mucor miehei) together with a Phospholipase A₂ from hog pancreas, enzyme selective for the sn-2-position; the best results were obtained carrying out the enzymatic reaction in a microemulsion system.     

Phospholipase-mediated preparation of 1-ricinoleoyl-2-acyl-sn- glycero-3-phosphocholine from soya and egg phosphatidylcholine

1-Ricinoleoyl-2-acyl-sn-glycero-3-phosphocholine was prepared by incorporating ricinoleic acid completely in the sn-1 position of egg and soya phosphatidylcholine (PC) using immobilized phospholipase A₁ as the catalyst. The optimum reaction conditions for maximum incorporation of ricinoleic acid into PC through transesterification were 10% (w/w) immobilized enzyme (116 mg), a 1:5 mol ratio of PC (soya, 387 mg; egg, 384 mg) to methyl ricinoleate (780 mg) at 50 °C for 24 h in hexane.     

Synthesis of azide and amide analogs of platelet-activating factor and related derivatives

2-Azido-2-deoxy-1-O-hexadecyl-sn-glycero-3-phosphorylcholine was prepared in good yield from D-mannitol via 3-O-hexadecyl-2-O-methanesulfonyl-1-O-triphenylmethyl-sn-glycerol. Nucleophilic displacement of the 2-methanesulfonate function by benzoate or azide ion proceeded with inversion of configuration (Sn2) without racemization. Hydrogenation of the azidophospholipid gave 2-amino-2-deoxy-1-O-hexadecyl-sn-glycero-3-phosphorylcholine which is a versatile intermediate for the preparation of amide analogs of platelet-activating factor and related derivatives. The synthesis of 2-deoxy-2-fluoro-1-O-hexadecyl-sn-glycero-3-phosphorylcholine was also described.     

Potent hypotensive activity of 1-O-hexadecyl-2-O-acetyl-sn-glycero-3-phosphocholine in spontaneously hypertensive rat

Chemically synthesized 1-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine possessed the most potent hypotensive activity compared with bradykinin, prostagrandin E₂ and I₂ when 5 nano moles/kg body weight of each drug were administered intravenously in spontaneously hypertensive rat. The potency and the duration of hypotensive activity of 1-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine were dose dependent. Exogenous norepinephrine or angiotensin II showed pressor activity during the hypotensive action of 1-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine, but did not disturb the hypotensive pattern of this ether lipid. These may suggest that 1-O-alkyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine plays an important role for the regulation of blood pressure.     

Acyl-chlorodeoxy-glycerophosphorylcholines,Part II: Total synthesis of “cyclic lysolecithin”

Reaction of 1-fattyacyl-sn-glycero-3-phosphorylcholine with triphenylphosphine — carbon tetrachloride gave 3-fattyacyl-2-chloro-2-deoxy-sn-glycero-1-phosphorylcholine together with small amounts of other chlorodeoxy isomers. 1-Chloro-1-deoxy-2-palmitoyl-rac-glycero-3-phosphorylcholine was prepared by total synthesis from 3-chloro-2-iodopropyl palmitate. The main step in the synthesis involves the nucleophilic displacement of iodide at C-2 with dibenzyl phosphate anion, which proceeds with an acyloxy migration, leading to the key intermediate 1-chloro-1-deoxy-2-palmitoyl-rac-glycero-3-(dibenzyl phosphate). Hydrogenolysis of this phosphate triester, followed by esterification with choline acetate gave the final product. The properties of the products support an earlier conclusion that the so-called “cyclic lysolecithin” is a mixture of isomeric acyl-chloro-deoxy-glycero-phosphorylcholines in which 1-chloro-1-deoxy-2-acyl-glycero-3-phosphorylcholine is the major component.