Identification of unusual oxysterols and bile acids with 7-oxo or 3β,5α,6β-trihydroxy functions in human plasma by charge-tagging mass spectrometry with multistage fragmentation.
Identification of unusual oxysterols and bile acids with 7-oxo or 3β,5α,6β-trihydroxy functions in human plasma by charge-tagging mass spectrometry with multistage fragmentation.
复制标题
DOI：
10.1194/jlr.d083246
复制
发表时间：
2018-06
影响因子：
6.5
通讯作者：
Wang Y
中科院分区：
文献类型：
--
作者：
Griffiths WJ;Gilmore I;Yutuc E;Abdel-Khalik J;Crick PJ;Hearn T;Dickson A;Bigger BW;Wu TH;Goenka A;Ghosh A;Jones SA;Wang Y
7-氧化胆固醇（7-OC）、5，6-环氧胆固醇（5，6-EC）及其水解产物胆甾烷-3 β，5 α，6 β-三醇（3β，5 α，6 β-三醇）通常是人体样本中的次要氧化固醇;然而，在疾病中，它们的水平可能会大大升高。这是来自患有一些溶酶体贮积症的患者的血浆的情况，例如，C型尼曼-匹克病，或甾醇代谢的先天性缺陷，例如，Smith-Lemli-Opitz综合征和肌腱黄瘤病。7-OC和5，6-EC分析中的一个复杂问题是，它们也可以在空气中处理样品期间从胆固醇离体形成，导致与体内形成的分子混淆。当内源性形成时，7-OC、5，6-EC和3β，5 α，6 β-三醇可转化为胆汁酸。在这里，我们描述了基于化学衍生化和LC/MS多级裂解（MSn）的方法，以鉴定7-OC转化为3β-羟基-7-氧代胆酚-5-烯酸和5，6-EC和3β，5 α，6 β-三醇转化为3β，5 α，6 β-三羟基胆烷酸的必要中间体。中间代谢物的鉴别通过其不寻常的MSn裂解模式来促进。半定量测量是可能的，但绝对值等待同位素标记的标准品的合成。
7-Oxocholesterol (7-OC), 5,6-epoxycholesterol (5,6-EC), and its hydrolysis product cholestane-3β,5α,6β-triol (3β,5α,6β-triol) are normally minor oxysterols in human samples; however, in disease, their levels may be greatly elevated. This is the case in plasma from patients suffering from some lysosomal storage disorders, e.g., Niemann-Pick disease type C, or the inborn errors of sterol metabolism, e.g., Smith-Lemli-Opitz syndrome and cerebrotendinous xanthomatosis. A complication in the analysis of 7-OC and 5,6-EC is that they can also be formed ex vivo from cholesterol during sample handling in air, causing confusion with molecules formed in vivo. When formed endogenously, 7-OC, 5,6-EC, and 3β,5α,6β-triol can be converted to bile acids. Here, we describe methodology based on chemical derivatization and LC/MS with multistage fragmentation (MSn) to identify the necessary intermediates in the conversion of 7-OC to 3β-hydroxy-7-oxochol-5-enoic acid and 5,6-EC and 3β,5α,6β-triol to 3β,5α,6β-trihydroxycholanoic acid. Identification of intermediate metabolites is facilitated by their unusual MSn fragmentation patterns. Semiquantitative measurements are possible, but absolute values await the synthesis of isotope-labeled standards.