Key Laboratory of Functional Small Organic Molecule, Jiangxi Normal University, Ministry of Education , Nanchang 330022, China.
State Key Laboratory of Food Science and Technology, Nanchang University , Nanchang 330047, China.
J Agric Food Chem. 2017 Aug 2;65(30):6179-6187. doi: 10.1021/acs.jafc.7b00934. Epub 2017 Jul 19.
Our previous study indicated that pretreatment by dynamic high-pressure microfluidization (DHPM) and glycation with galactose was a promising method for decreasing the immunoglobulin E (IgE)-binding ability of β-lactoglobulin (β-LG). In this work, the conformational alteration of β-LG subjected to DHPM and glycation treatment was investigated in relation to IgE-binding ability by orbitrap mass spectrometry. After DHPM pretreatment, lower IgE-binding ability of glycated β-LG was observed with increasing pressures. Prior to DHPM pretreatment, 11 glycated sites were identified, while the number of glycation sites was increased to 12 after pretreatment. However, there was no significant difference of the glycation sites at the pressures of 50, 100, and 200 MPa, respectively. Average degree of substitution per peptide molecule of β-LG (DSP) was investigated to assess the degree of glycation per glycation site. All of the samples pretreated by DHPM exhibited a higher glycation level than those without DHPM pretreatment. The shielding effects of epitopes owing to glycation contributed to the reduction of IgE-binding capacity. Orbitrap mass spectrometry could provide a comprehensive understanding of the nature of protein glycation.
我们之前的研究表明，动态高压微射流（DHPM）预处理和半乳糖糖化是降低β-乳球蛋白（β-LG）免疫球蛋白 E（IgE）结合能力的一种很有前途的方法。在这项工作中，通过轨道阱质谱研究了 DHPM 预处理和糖化处理后β-LG 的构象变化与 IgE 结合能力的关系。经过 DHPM 预处理后，随着压力的增加，糖化β-LG 的 IgE 结合能力降低。在 DHPM 预处理之前，鉴定出 11 个糖化位点，而预处理后糖化位点的数量增加到 12 个。然而，在压力分别为 50、100 和 200 MPa 时，糖化位点没有明显差异。研究了β-LG 每个肽分子的平均取代度（DSP），以评估每个糖化位点的糖化程度。所有经过 DHPM 预处理的样品的糖化水平均高于未经 DHPM 预处理的样品。由于糖化引起的表位的屏蔽效应导致 IgE 结合能力降低。轨道阱质谱可以提供对蛋白质糖化性质的全面了解。
