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标题：Elucidating the chemical structure of native 1-deoxysphingosine
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作者：Regula Steiner ; Essa M. Saied ; Alaa Othman 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2016
卷号：57
期号：7
页码：1194-1203
DOI：10.1194/jlr.M067033
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：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 (4 E ) 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(4 E )(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 MS² 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(14 Z ) and (14 E ) stereoisomers assigned the native compound to be SPH m18:1(14 Z ). This indicates that 1-deoxySLs are metabolized differently than canonical sphingolipids.
关键词：deoxysphingolipids ; double bond position ; dimethyl disulfide adducts ; mass spectrometry ; differential-mobility spectrometry ; ozone-induced dissociation ; structural isomers