Kohansal-Nodehi M, Swiatek-de Lange M, Tabarés G, Busskamp H
Early Development and Reagent Design, Roche Diagnostics GmbH, Penzberg, Germany.
J Mass Spectrom Adv Clin Lab. 2022 Jul 25;25:61-70. doi: 10.1016/j.jmsacl.2022.07.001. eCollection 2022 Aug.
Haptoglobin (Hp) is an abundant acute-phase protein secreted mainly by the liver into the bloodstream. There are three Hp protein phenotypes (Hp type 1-1, 2-1, and 2-2), which differ in the number of α- and β-chains, type of α-chain (the β-chain type remains the same in all the Hp phenotypes), and the polymers that they form via disulfide bonds. Hp has four N-glycosylation sites on the β-chain. Glycosylation of Hp has been reported frequently as a potential glycobiomarker for many diseases; however, whether Hp polymorphism affects its glycosylation has not yet been addressed extensively or in depth.
This study investigated the differences between the glycosylation patterns of Hp phenotypes using serum from 12 healthy individuals (four for each Hp phenotype).
An efficient method for isolating Hp from serum was established and subsequently the Hp phenotype of each sample was characterized by immunoblotting. Then, LC-MS/MS analysis of isolated Hp after treatment with three exoglycosidases (sialidase, α2-3 neuraminidase, Endo F3) was performed to characterize the glycosylation pattern of Hp for each individual sample.
The data reveal significant differences among the branching, sialylation, and fucosylation of Hp types, documenting the effect of Hp polymorphism on its glycosylation.
Overall, the study suggests that Hp phenotype characterization should be considered during the investigation of Hp glycosylation.
触珠蛋白（Hp）是一种主要由肝脏分泌到血液中的丰富的急性期蛋白。有三种Hp蛋白表型（Hp 1-1型、2-1型和2-2型），它们在α链和β链的数量、α链的类型（所有Hp表型中的β链类型相同）以及它们通过二硫键形成的聚合物方面存在差异。Hp在β链上有四个N-糖基化位点。Hp的糖基化经常被报道为许多疾病的潜在糖生物标志物；然而，Hp多态性是否影响其糖基化尚未得到广泛或深入的研究。
本研究使用12名健康个体（每种Hp表型4名）的血清，研究Hp表型糖基化模式之间的差异。
建立了一种从血清中分离Hp的有效方法，随后通过免疫印迹对每个样品的Hp表型进行表征。然后，对用三种外切糖苷酶（唾液酸酶、α2-3神经氨酸酶、内切糖苷酶F3）处理后的分离Hp进行液相色谱-串联质谱（LC-MS/MS）分析，以表征每个个体样品中Hp的糖基化模式。
数据揭示了Hp各类型在分支、唾液酸化和岩藻糖基化方面存在显著差异，证明了Hp多态性对其糖基化的影响。
总体而言，该研究表明在研究Hp糖基化时应考虑Hp表型特征。
