| Apolipoproteins regulate the kinetics of endothelial lipase-mediated hydrolysis of phospholipids in reconstituted high-density lipoproteins. | |
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MedLine Citation:
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PMID: 15362876 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Endothelial lipase (EL) is a newly identified member of the triglyceride lipase gene family that hydrolyzes high-density lipoprotein (HDL) phospholipids. This study investigates the ability of the major apolipoproteins of rHDL to regulate the kinetics of EL-mediated phospholipid hydrolysis in well-characterized, homogeneous preparations of spherical rHDL. The rHDL contained either apoA-I as the only apolipoprotein, (A-I)rHDL, apoA-II as the only apolipoprotein, (A-II)rHDL, or apoA-I as well as apoA-II, (A-I/A-II)rHDL. The rHDL were comparable in terms of size and lipid composition and contained cholesteryl esters (CE) as their sole core lipid. Phospholipid hydrolysis was quantitated as the mass of nonesterified fatty acids (NEFA) released from the rHDL during incubation with EL. The V(max) of phospholipid hydrolysis for (A-I/A-II)rHDL [391.9 +/- 12.9 nmol of NEFA formed (mL of EL)(-1) h(-1)] was greater than (A-I)rHDL [152.8 +/- 4.7 nmol of NEFA formed (mL of EL)(-1) h(-1)]. The energy of activation (E(a)) for the hydrolysis reactions was calculated to be 52.1 and 34.8 kJ mol(-1) for (A-I)rHDL and (A-I/A-II)rHDL, respectively. Minimal phospholipid hydrolysis was observed for the (A-II)rHDL. Kinetic analysis showed that EL has a higher affinity for the phospholipids in (A-I)rHDL [K(m)(app) = 0.10 +/- 0.01 mM] than in (A-I/A-II)rHDL [K(m)(app) = 0.27 +/- 0.03 mM]. Furthermore, (A-I)rHDL is a competitive inhibitor of the EL-mediated phospholipid hydrolysis of (A-I/A-II)rHDL. These results establish that apolipoproteins are major determinants of the kinetics of EL-mediated phospholipid hydrolysis in rHDL. |
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Authors:
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Daniela Caiazza; Anisa Jahangiri; Daniel J Rader; Dawn Marchadier; Kerry-Anne Rye |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biochemistry Volume: 43 ISSN: 0006-2960 ISO Abbreviation: Biochemistry Publication Date: 2004 Sep |
Date Detail:
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Created Date: 2004-09-14 Completed Date: 2004-11-01 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: United States |
Other Details:
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Languages: eng Pagination: 11898-905 Citation Subset: IM |
Affiliation:
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Lipid Research Group, The Heart Research Institute, Camperdown, Sydney, NSW 2050, Australia. d.caiazza@hri.org.au |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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1,2-Dipalmitoylphosphatidylcholine
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metabolism* Animals Apolipoprotein A-I / metabolism* Apolipoprotein A-II / metabolism* COS Cells Cercopithecus aethiops Humans Lipase / metabolism* Lipoproteins, HDL / metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Apolipoprotein A-I; 0/Apolipoprotein A-II; 0/Lipoproteins, HDL; 2644-64-6/1,2-Dipalmitoylphosphatidylcholine; EC 3.1.1.-/LIPG protein, human; EC 3.1.1.3/Lipase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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