title: Stable carbon isotope discrimination by human 3-hydroxy-3-methylglutaryl-coenzyme A reductase.
abstract: The aim of this study was to investigate the possible existence and magnitude of stable carbon isotope discrimination by human 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). The catalytic portion of HMGR was expressed and purified. The reaction product mevalonate was lactonized and extracted from the reaction mixture by a solid-phase extraction protocol. Stable carbon isotope ratios of mevalonolactone (MVL) were analyzed by gas chromatography-combustion-isotope ratio mass spectrometry. An average fractionation factor (12)k/(13)k of 1.0031 +/- 0.0004 for all carbon atoms contained in MVL was estimated by the method of internal competition. The value was calculated by nonlinear curve fitting, where the ratio (13)C/(12)C of MVL was plotted versus the fraction of reaction.
authors.affiliation: Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany. s.luedke@biochem.dshs-koeln.de
authors.forename: Svena M
authors.initials: SM
authors.lastname: Lüdke
authors.forename: Ulrich
authors.initials: U
authors.lastname: Flenker
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Schänzer
authors.forename: Dietmar
authors.initials: D
authors.lastname: Schomburg
mesh_terms: D002247:Carbon Isotopes / Q000032:analysis / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000032:analysis*; D008798:Mevalonic Acid / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D002247:Carbon Isotopes; C015367:mevalonolactone; D006903:Hydroxymethylglutaryl CoA Reductases; D008798:Mevalonic Acid