Low-pressure pH gradient ion exchange separation provides a fast, simple and cost-effective method for preparative purification of native and desialylated apo-transferrin. The method enables easy monitoring of the extent of the desialylation reaction and also the efficient separation and purification of protein fractions after desialylation. The N-glycan analysis shows that the modified desialylation protocol successfully reduces the content of the sialylated fractions relative to the native apo-transferrin. In the optimized protocol, the desialylation capacity is increased by 150 %, compared to the original protocol provided by the manufacturer. The molar absorption coefficients in the near-UV region for the native and desialylated apo-transferrin differ by several percent, suggesting a subtle dependence of the glycoprotein absorbance on the variable sialic acid content. The method can easily be modified for other glycoproteins and is particularly appropriate for quick testing of sialic acid content in the protein glycosylation patterns prior to further verification by mass spectrometry.

低压 pH 梯度离子交换分离为天然和脱唾液酸化载脂蛋白转铁蛋白的制备纯化提供了一种快速、简单且经济高效的方法。该方法能够轻松监测脱唾液酸化反应的程度以及脱唾液酸化后蛋白质级分的有效分离和纯化。N-聚糖分析表明，相对于天然载脂蛋白转铁蛋白，修改后的去唾液酸化方案成功地降低了唾液酸化部分的含量。在优化的方案中，与制造商提供的原始方案相比，脱唾液酸能力提高了 150%。天然和去唾液酸化的载脂蛋白转铁蛋白在近紫外区域的摩尔吸收系数相差几个百分点，表明糖蛋白吸光度对可变唾液酸含量有微妙的依赖性。该方法可以很容易地针对其他糖蛋白进行修改，特别适用于在通过质谱法进一步验证之前快速测试蛋白质糖基化模式中的唾液酸含量。