title: Elucidating the chemical structure of native 1-deoxysphingosine.
abstract: The 1-deoxysphingolipids (1-deoxySLs) are formed by an alternate substrate usage of the enzyme, serine-palmitoyltransferase, and are devoid of the C1-OH-group present in canonical sphingolipids. Pathologically elevated 1-deoxySL levels are associated with the rare inherited neuropathy, HSAN1, and diabetes type 2 and might contribute to β cell failure and the diabetic sensory neuropathy. In analogy to canonical sphingolipids, it was assumed that 1-deoxySLs also bear a (4E) double bond, which is normally introduced by sphingolipid delta(4)-desaturase 1. This, however, was never confirmed. We therefore supplemented HEK293 cells with isotope-labeled D3-1-deoxysphinganine and compared the downstream formed D3-1-deoxysphingosine (1-deoxySO) to a commercial synthetic SPH m18:1(4E)(3OH) standard. Both compounds showed the same m/z, but differed in their RPLC retention time and atmospheric pressure chemical ionization in-source fragmentation, suggesting that the two compounds are structural isomers. Using dimethyl disulfide derivatization followed by MS(2) as well as differential-mobility spectrometry combined with ozone-induced dissociation MS, we identified the carbon-carbon double bond in native 1-deoxySO to be located at the (Δ14) position. Comparing the chromatographic behavior of native 1-deoxySO to chemically synthesized SPH m18:1(14Z) and (14E) stereoisomers assigned the native compound to be SPH m18:1(14Z). This indicates that 1-deoxySLs are metabolized differently than canonical sphingolipids.
authors.affiliation: Institute of Clinical Chemistry, University and University Hospital of Zurich, CH-8091 Zurich, Switzerland.
authors.forename: Regula
authors.initials: R
authors.lastname: Steiner
authors.affiliation: Institute for Chemistry, Humboldt Universität zu Berlin, 12489 Berlin, Germany; Chemistry Department, Faculty of Science, Suez Canal University, Ismailia, Egypt.
authors.forename: Essa M
authors.initials: EM
authors.lastname: Saied
authors.affiliation: Institute of Clinical Chemistry, University and University Hospital of Zurich, CH-8091 Zurich, Switzerland.
authors.forename: Alaa
authors.initials: A
authors.lastname: Othman
authors.affiliation: Institute for Chemistry, Humboldt Universität zu Berlin, 12489 Berlin, Germany; Chemistry Department, Faculty of Science, Suez Canal University, Ismailia, Egypt.
authors.forename: Christoph
authors.initials: C
authors.lastname: Arenz
authors.affiliation: Mass Spectrometry User Resource and Research Facility, School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Alan T
authors.initials: AT
authors.lastname: Maccarone
authors.affiliation: Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4001, Australia.
authors.forename: Berwyck L J
authors.initials: BL
authors.lastname: Poad
authors.affiliation: Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4001, Australia.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blanksby
authors.affiliation: Institute of Clinical Chemistry, University and University Hospital of Zurich, CH-8091 Zurich, Switzerland.
authors.forename: Arnold
authors.initials: A
authors.lastname: von Eckardstein
authors.affiliation: Institute of Clinical Chemistry, University and University Hospital of Zurich, CH-8091 Zurich, Switzerland thorsten.hornemann@usz.ch.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Hornemann
mesh_terms: D002244:Carbon / Q000737:chemistry; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D003929:Diabetic Neuropathies / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D057809:HEK293 Cells; D009477:Hereditary Sensory and Autonomic Neuropathies / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008055:Lipids; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D051102:Serine C-Palmitoyltransferase / Q000737:chemistry / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism
chemical_list: C514304:1-deoxysphingosine; D008055:Lipids; D002244:Carbon; D010088:Oxidoreductases; C115532:sphingolipid desaturase; D051102:Serine C-Palmitoyltransferase; D013110:Sphingosine; C408363:spisulosine
keywords: deoxysphingolipids; differential-mobility spectrometry; dimethyl disulfide adducts; double bond position; mass spectrometry; ozone-induced dissociation; structural isomers