title: Measurement of the phospholipase activity of endothelial lipase in mouse plasma.
abstract: Endothelial lipase (EL) is a major negative regulator of plasma HDL levels in mice, rabbits, and most probably, humans. Although this regulatory function is critically dependent on EL's hydrolysis of HDL phospholipids, as yet there is no phospholipase assay specific for EL in plasma. We developed such an assay for the mouse enzyme using a commercially available phospholipid-like fluorescent substrate in combination with an EL neutralizing antibody. The specificity of the assay was established using EL knockout mice and its utility demonstrated by detection of an increase in plasma EL phospholipase activity following exposure of wild-type mice to lipopolysaccharide. The assay revealed that murine pre-heparin plasma does not contain measurable EL activity, indicating that the hydrolysis of HDL phospholipids by EL in vivo likely occurs on the cell surface.
authors.affiliation: Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY 11203, USA.
authors.forename: Debapriya
authors.initials: D
authors.lastname: Basu
authors.forename: Xia
authors.initials: X
authors.lastname: Lei
authors.forename: Joby
authors.initials: J
authors.lastname: Josekutty
authors.forename: M Mahmood
authors.initials: MM
authors.lastname: Hussain
authors.forename: Weijun
authors.initials: W
authors.lastname: Jin
mesh_terms: D000818:Animals; D001896:Boron Compounds / Q000737:chemistry / Q000378:metabolism; D057075:Enzyme Assays / Q000379:methods*; D006493:Heparin / Q000494:pharmacology; D008049:Lipase / Q000097:blood* / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008246:Lysophospholipids / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D054466:Phospholipases A1 / Q000378:metabolism*
chemical_list: D001896:Boron Compounds; D008070:Lipopolysaccharides; D008246:Lysophospholipids; C557974:N-((6-(2,4-dinitrophenyl)amino)hexanoyl)-1-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-2-hexyl-sn-glycero-3-phosphoethanolamine; D006493:Heparin; D008049:Lipase; C498741:Lipg protein, mouse; D054466:Phospholipases A1