Changes in human IgG galactosylation and sialylation have been associated with several inflammatory diseases which are a major burden on the health care system. A large body of work on well-established glycomic and glycopeptidomic assays has repeatedly demonstrated inflammation-induced changes in IgG glycosylation. However, these assays are usually based on specialized analytical instrumentation which could be considered a technical barrier for uptake by some laboratories. Hence there is a growing demand for simple biochemical assays for analyzing these glycosylation changes. We have addressed this need by introducing a novel glycosidase plate-based assay for the absolute quantification of galactosylation and sialylation on IgG. IgG glycoproteins are treated with specific exoglycosidases to release the galactose and/or sialic acid residues. The released galactose monosaccharides are subsequently used in an enzymatic redox reaction that produces a fluorescence signal that is quantitative for the amount of galactosylation and, in-turn, sialylation on IgG. The glycosidase plate-based assay has the potential to be a simple, initial screening assay or an alternative assay to the usage of high-end analytical platforms such as HILIC-FLD-MSn when considering the analysis of galactosylation and sialylation on IgG. We have demonstrated this by comparing our assay to an industrial established HILIC-FLD-MSn glycomic analysis of 15 patient samples and obtained a Pearson’s r correlation coefficient of 0.8208 between the two methods.

人类 IgG 半乳糖基化和唾液酸化的变化与几种炎症性疾病有关，这些疾病是卫生保健系统的主要负担。大量关于成熟的糖组学和糖肽组学分析的工作一再证明炎症诱导的 IgG 糖基化变化。然而，这些测定通常基于专门的分析仪器，这可能被一些实验室认为是技术障碍。因此，对分析这些糖基化变化的简单生化分析的需求不断增长。我们通过引入一种新的基于糖苷酶板的测定法来对 IgG 上的半乳糖基化和唾液酸化进行绝对定量，从而满足了这一需求。IgG 糖蛋白用特定的外切糖苷酶处理以释放半乳糖和/或唾液酸残基。释放的半乳糖单糖随后用于酶促氧化还原反应，该反应产生荧光信号，该信号对 IgG 上的半乳糖基化和唾液酸化的量进行定量。在考虑分析 IgG 上的半乳糖基化和唾液酸化时，基于糖苷酶板的检测有可能成为一种简单的初始筛选检测或替代高端分析平台（如 HILIC-FLD-MSn）的使用。我们已经通过将我们的检测与工业建立的 HILIC-FLD-MSn 糖组分析对 15 个患者样本进行比较来证明这一点，并在两种方法之间获得了 0.8208 的 Pearson's r 相关系数。