title: Sensitive assay for hormone-sensitive lipase using NBD-labeled monoacylglycerol to detect low activities in rat adipocytes.
abstract: The recent finding that p-nitrobenzofurazan (NBD)-FA is incorporated into and released from the acylglycerols of isolated rat adipocytes in an insulin-sensitive manner [G. Muller, H. Jordan, C. Jung, H. Kleine, and S. Petry. 2003. Biochimie. 85: 1245-1246] suggests that NBD-FA-labeled acylglycerols are cleaved by rat adipocyte hormone-sensitive lipase (HSL) in vivo. In the present study, we developed a continuous, sensitive in vitro lipase assay using a monoacylglycerol (MAG) containing NBD (NBD-MAG). NBD-MAG was found to provide an efficient substrate for rat adipocyte and human recombinant HSL. Ultrasonic treatment applied in the presence of phospholipids leads to the incorporation of NBD-MAG into the phospholipid liposomes and to a concomitant change of its spectrophotometric properties. The enzymatic release of NBD-FA and its dissociation from the carrier liposomes is accompanied by the recovery of the original spectrophotometric characteristics. The rate of lipolysis was monitored by measuring the increase in optical density at 481 nm, which was found to be linear with time and linearly proportional to the amount of lipase added. To assess the specific activity of recombinant HSL, we determined the molar extinction coefficient of NBD-FA under the assay conditions. This convenient assay procedure based on NBD-MAG should facilitate the search for small molecule HSL inhibitors.
authors.affiliation: Aventis Pharma Germany, 65926 Frankfurt am Main, Germany. abousal@ibsm.cnrs-mrs.fr
authors.forename: Stefan
authors.initials: S
authors.lastname: Petry
authors.forename: Yassine
authors.initials: Y
authors.lastname: Ben Ali
authors.forename: Henri
authors.initials: H
authors.lastname: Chahinian
authors.forename: Holger
authors.initials: H
authors.lastname: Jordan
authors.forename: Horst
authors.initials: H
authors.lastname: Kleine
authors.forename: Günter
authors.initials: G
authors.lastname: Müller
authors.forename: Frédéric
authors.initials: F
authors.lastname: Carrière
authors.forename: Abdelkarim
authors.initials: A
authors.lastname: Abousalham
mesh_terms: D017667:Adipocytes / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D002457:Cell Extracts / Q000737:chemistry; D005989:Glycerides / Q000138:chemical synthesis / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry; D015394:Molecular Structure; D010069:Oxadiazoles / Q000138:chemical synthesis / Q000737:chemistry*; D051381:Rats; D011994:Recombinant Proteins / Q000032:analysis / Q000378:metabolism; D012680:Sensitivity and Specificity; D013010:Sonication; D013053:Spectrophotometry / Q000379:methods; D002787:Sterol Esterase / Q000032:analysis* / Q000378:metabolism*; D013379:Substrate Specificity / Q000502:physiology; D013997:Time Factors
chemical_list: D002457:Cell Extracts; D005989:Glycerides; D008081:Liposomes; D010069:Oxadiazoles; D011994:Recombinant Proteins; C011514:4-nitrobenzofurazan; D002787:Sterol Esterase