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Anal Biochem. 2018 May 15;549:164-170. doi: 10.1016/j.ab.2018.03.024. Epub 2018 Mar 30.

A fluorometric assay for lysosomal phospholipase A2 activity using fluorescence-labeled truncated oxidized phospholipid.

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Department of Ophthalmology, School of Medicine, Sapporo Medical University, Sapporo, Japan. Electronic address:
Department of Ophthalmology, School of Medicine, Sapporo Medical University, Sapporo, Japan.
Department of Internal Medicine, University of Michigan Medical School, University of Michigan, Ann Arbor, MI, USA.


Lysosomal phospholipase A2 (LPLA2) is a key enzyme involved in the homeostasis of cellular phospholipids. Recently, LPLA2 was reported to preferentially degrade some truncated oxidized phospholipids at the sn-1 position. A commercially available, truncated oxidized phospholipid conjugated with a fluorescent dye, 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphoethanolamine-N-[4-(dipyrrometheneboron difluoride) butanoyl] (PGPE-BODIPY), was used to develop a specific assay for this enzyme. When recombinant mouse LPLA2 was incubated with liposomes consisting of 1,2-O-octadecyl-sn-glycero-3-phosphocholine/PGPE-BODIPY under acidic conditions, PGPE-BODIPY was converted to palmitic acid and a polar BODIPY-product. After phase partitioning by chloroform/methanol, the polar BODIPY-product was recovered in the aqueous phase and identified as 1-lyso-PGPE-BODIPY. The formation of 1-lyso-PGPE-BODIPY was quantitatively determined by fluorescent measurements. The Km and Vmax values of the recombinant LPLA2 for PGPE-BODIPY were 5.64 μM and 20.7 μmol/min/mg protein, respectively. Detectable activity against PGPE-BODIPY was present in LPLA2 deficient mouse sera, but the deacylase activity was completely suppressed by treatment with 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF). AEBSF had no effect on LPLA2 activity. The LPLA2 activity of mouse serum pre-treated with AEBSF was specifically and quantitatively determined by this assay method. The PGPE-BODIPY and AEBSF based LPLA2 assay is convenient and can be used to measure LPLA2 activity in a variety of biological specimens.


Fluorescence-labeled oxidized phospholipid; Lysosomal phospholipase A2; Truncated oxidized phospholipid; sn-1 preference

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