Synthetic standard aided quantification and structural characterization of amyloid-beta glycopeptides enriched from cerebrospinal fluid of Alzheimer's disease patients
Synthetic standard aided quantification and structural characterization of amyloid-beta glycopeptides enriched from cerebrospinal fluid of Alzheimer's disease patients
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DOI：
10.1038/s41598-019-41897-5
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发表时间：
2019-04-02
影响因子：
4.6
通讯作者：
Larson, Goran
中科院分区：
文献类型：
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作者：
Nilsson, Jonas;Brinkmalm, Gunnar;Larson, Goran
阿尔茨海默病（AD）的早期病理学标志是淀粉样蛋白-β（A β）在脑中的沉积，其主要由源自淀粉样蛋白前体蛋白（APP）的长达43个氨基酸的A β肽组成。我们先前从人脑脊液（CSF）中鉴定了一系列15-20个残基长的唾液酸化Tyr-10 O-糖基化A β肽，并观察到AD患者与非AD患者相比这些肽相对增加。我们在此报道了同位素双标记的A β 1-15糖肽的合成和使用，该糖肽携带核心1Gal β 3GalNAc α 1-O-Tyr-10结构，（1）通过HCD LC-MS/MS鉴定人CSF中免疫纯化和去唾液酸化A β糖肽的明确聚糖核心1结构，并（2）建立去唾液酸化A β 1-15的LC-MS/MS定量方法（和A β-17）糖肽的浓度，以及（3）比较来自20名AD患者和20名健康对照的CSF中这些A β糖肽的浓度。尽管我们明确鉴定了糖肽的核心1结构和Tyr-10连接位点，但我们没有观察到AD组和非AD组之间脱唾液酸化A β 1-15或A β 1-17糖肽的任何定量差异（通过肽和氧鎓离子片段测定）。新的定量糖蛋白质组学方法描述，使用双标记的糖肽标准，无疑将促进糖肽作为临床生物标志物的未来研究，但也应该包括唾液酸化的A β标准，以揭示特定的唾液酸化模式的个别A β糖肽在AD患者和对照。
An early pathological hallmark of Alzheimer's disease (AD) is amyloid-beta (A beta) deposits in the brain, which largely consist of up to 43 amino acids long A beta peptides derived from the amyloid precursor protein (APP). We previously identified a series of sialylated Tyr-10 O-glycosylated A beta peptides, 15-20 residues long, from human cerebrospinal fluid (CSF) and observed a relative increase of those in AD vs non-AD patients. We report here on the synthesis and use of an isotopically double-labeled A beta 1-15 glycopeptide, carrying the core 1Gal beta 3GalNAc alpha 1-O-Tyr-10 structure, to (1) identify by HCD LC-MS/MS the definite glycan core 1 structure of immunopurified and desialylated A beta glycopeptides in human CSF and to (2) establish a LC-MS/MS quantification method for desialylated A beta 1-15 (and A beta-17) glycopeptides and to (3) compare the concentrations of these A beta glycopeptides in CSF from 20 AD patients and 20 healthy controls. Although we unambiguously identified the core 1 structures and Tyr-10 attachment sites of the glycopeptides, we did not observe any quantitative differences, determined through both peptide and oxonium ion fragments, of the desialylated A beta 1-15 or A beta 1-17 glycopeptides between the AD and non-AD group. The new quantitative glycoproteomic approach described, using double-labeled glycopeptide standards, will undoubtedly facilitate future studies of glycopeptides as clinical biomarkers but should also embrace sialylated A beta standards to reveal specific sialylation patterns of individual A beta glycopeptides in AD patients and controls.