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Journal of Lipid Research, Vol. 46, 994-1000, May 2005
Copyright © 2005 by American Society for Biochemistry and Molecular Biology

Continuous monitoring of cholesterol oleate hydrolysis by hormone-sensitive lipase and other cholesterol esterases

Yassine Ben Ali^*, Frédéric Carrière^*, Robert Verger^*, Stefan Petry, Günter Muller and Abdelkarim Abousalham^1,*

^* Enzymology at Interfaces and Physiology of Lipolysis, Unité Propre de Recherche 9025, Centre National de la Recherche Scientifique, 13402 Marseille Cedex 20, France
Sanofi Aventis Germany, 65926 Frankfurt am Main, Germany

Published, JLR Papers in Press, February 16, 2005. DOI 10.1194/jlr.M400509-JLR200

¹ To whom correspondence should be addressed. e-mail: abousal{at}ibsm.cnrs-mrs.fr

Hormone-sensitive lipase (HSL) contributes importantly to the hydrolysis of cholesteryl ester in steroidogenic tissues, releasing the cholesterol required for adrenal steroidogenesis. HSL has broad substrate specificity, because it hydrolyzes triacylglycerols (TAGs), diacylglycerols, monoacylglycerols, and cholesteryl esters. In this study, we developed a specific cholesterol esterase assay using cholesterol oleate (CO) dispersed in phosphatidylcholine and gum arabic by sonication. To continuously monitor the hydrolysis of CO by HSL, we used the pH-stat technique. For the sake of comparison, the hydrolysis of CO dispersion was also tested using other cholesteryl ester-hydrolyzing enzymes. The specific activities measured on CO were found to be 18, 100, 27, and 3 µmol/min/mg for HSL, cholesterol esterase from Pseudomonas species, Candida rugosa lipase-3, and cholesterol esterase from bovine pancreas, respectively. The activity of HSL on CO is 4- to 5-fold higher than on long-chain TAGs. In contrast, with all other enzymes tested, the rates of TAG hydrolysis were higher than those of CO hydrolysis. The relatively higher turnover of HSL on CO observed in vitro adds further molecular insight on the physiological importance of HSL in cholesteryl ester catabolism in vivo.

Thus, HSL could be considered more as a cholesteryl ester hydrolase than as a TAG lipase.

Abbreviations: ß-CD, ß-cyclodextrin; CO, cholesterol oleate; CRL-3, Candida rugosa lipase-3; DAG, diacylglycerol; DGL, dog gastric lipase; FID, flame ionization detection; GA, gum arabic; HPL, human pancreatic lipase; HSL, hormone-sensitive lipase; MAG, monoacylglycerol; NaTDC, sodium taurodeoxycholate; PC, phosphatidylcholine; PCE, cholesterol esterase from bovine pancreas; PI, phosphatidylinositol; PsCE, cholesterol esterase from Pseudomonas species; TAG, triacylglycerol

Supplementary key words cholesterol ester hydrolase • triacylglycerol lipase • cholesterol oleate emulsion

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