Hydrolysis of polyhydroxy polyunsaturated fatty acid-glycerophosphocholines by Group IIA, V, and X secretory phospholipases A.

It is widely accepted that unesterified polyunsaturated ω-6 and ω-3 fatty acids (PUFA) are converted through various lipoxygenases, cyclooxygenases, and cytochrome P450 enzymes to a range of oxygenated derivatives (oxylipins), among which the polyhydroxides of unesterified PUFA have recently been recognized as cell signaling molecules with anti-inflammatory and pro-resolving properties, known as specialized pro-resolving mediators (SPMs). This study investigates the mono-, di-, and trihydroxy 16:0/PUFA-GPCs, and the corresponding 16:0/SPM-GPC, in plasma lipoproteins. We describe the isolation and identification of mono-, di-, and trihydroxy AA, EPA, and DHA-GPC in plasma LDL, HDL, HDL3, and acute phase HDL using normal phase LC/ESI-MS, as previously reported.

Destruction of polyunsaturated alkyl/acyl and alkenyl/acyl glycerophosphocholine of plasma lipoproteins during incubation with group V and X secretory phospholipase A s.

Plasma lipoproteins are carriers of various glycerophospholipids including diacyl, alkenyl/acyl, and alkyl/acyl glycerophosphocholines (GPCs), which become distributed among cells and tissues during metabolism. For metabolic function, these phospholipids require hydrolysis by phospholipases, but the responsible enzymes have not been identified. We had previously shown that after complete digestion of lipoprotein diacyl- and oxo-diacyl-GPCs, degradation of residual alkyl/acyl and alkenyl/acyl GPCs continues, despite the fact that ether lipids are resistant to hydrolysis by Ca -activated secretory PLA s and require the presence of the Ca -independent PLA .

Hydrolysis of glycerophosphocholine epoxides by human group IIA, V, and X secretory phospholipases A.

This study was prompted by recent reports that epoxyeicosatrienoic (EET) and epoxyeicosatetraenoic (EEQ) acids accelerate tumor growth and metastasis by stimulation of angiogenesis, while eicosapentaenoic (EPA) and epoxydocosapentaenoic (EDP) acids inhibit angiogenesis, tumor growth, and metastasis. Cytochrome P450 epoxygenases convert arachidonic to EET, eicosapentaenoic acid to EEQ, and docosahexaenoic acid to EDP, which are found both in free form and esterified to glycerophosphocholine (GPC). Both free and esterified epoxy (EP) acids are also formed during lipid autoxidation.

Hydrolysis of Phosphatidylcholine-Isoprostanes (PtdCho-IP) by Peripheral Human Group IIA, V and X Secretory Phospholipases A (sPLA).

Biologically active F- and E/D-type-prostane ring isomers (F-IP and E/D-IP, respectively) are produced in situ by non-enzymatic peroxidation of arachidonic acid esterified to GroPCho (PtdCho-IP) and are universally distributed in tissue lipoproteins and cell membranes. Previous work has shown that platelet-activating factor acetylhydrolases (PAF-AH) are the main endogenous PLA involved in degradation of PtdCho-IP. The present study shows that the PtdCho-IP are also subject to hydrolysis by group IIA, V and X secretory PLA, which also have a wide peripheral tissue distribution.

Enantioseparation of hydroxyeicosatetraenoic acids by hydroxypropyl-γ-cyclodextrin-modified micellar electrokinetic chromatography.

Complete resolution of hydroxyeicosatetraenoic acid (HETE) enantiomers was achieved using hydroxypropyl-γ-cyclodextrin (HP-γ-CD)-modified MEKC. The optimum running conditions were determined to be utilizing a 30 mM phosphate-15 mM borate buffer (pH 9.0) containing 30 mM HP-γ-CD and 75 mM SDS as the BGE, application of +30 kV as the effective voltage, and carrying out the experiment at 15°C.