title: In vitro organic nitrate bioactivation to nitric oxide by recombinant aldehyde dehydrogenase 3A1.
abstract: Organic nitrates (ORNs) are commonly used anti-ischemic and anti-anginal agents, which serve as an exogenous source of the potent vasodilator nitric oxide (NO). Recently, both mitochondrial aldehyde dehydrogenase-2 (ALDH2) and cytosolic aldehyde dehydrogenase-1a1 (ALDH1A1) have been shown to exhibit the ability to selectively bioactivate various ORNs in vitro. The objective of the present research was to examine the potential role of ALDH3A1, another major cytosolic isoform of ALDH, in the in vitro bioactivation of various ORNs, and to estimate the enzyme kinetic parameters toward ORNs through mechanistic modeling. The extent of bioactivation was assayed by exposing recombinant ALDH3A1 to various concentrations of ORNs, and measuring the concentration-time profiles of released NO via a NO-specific electrode. Metabolite formation kinetics was monitored for nitroglycerin (NTG) using LC/MS/MS. Our results showed that ALDH3A1 mRNA and protein were highly expressed in C57BL/6 mouse aortic, cardiac, and hepatic tissues, and it was able to release NO from several ORNs, including NTG, isosorbide dinitrate (ISDN), isosorbide-2-mononitrate (IS-2-MN), and nicorandil with similar Vmax (0.175-0.503nmol/min/mg of ALDH3A1), and Km values of 4.01, 46.5, 818 and 5.75×10(3)μM, respectively. However, activation of isosorbide-5-mononitrate (IS-5-MN) by ALDH3A1 was undetectable in vitro. ALDH3A1 was also shown to denitrate NTG, producing primarily glyceryl 1,2-dinitrate (1,2-GDN) in preference to glyceryl 1,3-dinitrate (1,3-GDN). Therefore, ALDH3A1 may contribute to the bioactivation of ORNs in vivo.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY 14214, United States.
authors.forename: Shunxin
authors.initials: S
authors.lastname: Lin
authors.forename: Nathaniel A
authors.initials: NA
authors.lastname: Page
authors.forename: Sun Mi
authors.initials: SM
authors.lastname: Fung
authors.forename: Ho-Leung
authors.initials: HL
authors.lastname: Fung
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001011:Aorta / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009566:Nitrates / Q000032:analysis / Q000378:metabolism*; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D005996:Nitroglycerin / Q000032:analysis / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism*
chemical_list: D000444:Aldehyde Dehydrogenase; D009566:Nitrates; D009569:Nitric Oxide; D005996:Nitroglycerin; D011994:Recombinant Proteins; C105543:Aldh3a1 protein, mouse
keywords: Aldehyde dehydrogenase 3A1; Kinetics; Nitric oxide; Organic nitrates