Department of Biotechnology, Bartın University, Kutlubey Campus, Bartın 74100, Turkey.
Department of Mechanical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Molecules. 2021 Nov 10;26(22):6799. doi: 10.3390/molecules26226799.
The aim of this study was to investigate binding interactions between β-lactoglobulin (BLG) and two different mucins, bovine submaxillary mucins (BSM) and porcine gastric mucin (PGM), using intrinsic and extrinsic fluorescence spectroscopies. Intrinsic fluorescence spectra showed an enhanced decrease of fluorescence intensity of BLG at all pH conditions when BLG was mixed with PGM rather than with BSM. We propose that, unlike BSM, the tertiary structure of PGM changes and the hydrophobic regions are exposed at pH 3 due to protonation of negatively charged residues. Results suggest that PGM also facilitated the structural unfolding of BLG and its binding with PGM by a hydrophobic interaction, especially at acidic pH, which was further supported by extrinsic fluorescence spectroscopy. Hydrophobic interaction is suggested as the dominant interaction mechanism between BLG and PGM at pH 3, whereas electrostatic interaction is the dominant one between BLG and BSM.
本研究旨在利用内源和外源荧光光谱法研究β-乳球蛋白（BLG）与两种不同粘蛋白（牛颌下腺粘蛋白（BSM）和猪胃粘蛋白（PGM））之间的结合相互作用。内源荧光光谱显示，在所有 pH 条件下，与 PGM 混合而非 BSM 混合时，BLG 的荧光强度均明显降低。我们提出，与 BSM 不同，PGM 的三级结构在 pH 3 时会发生变化，由于带负电荷的残基质子化，疏水区会暴露出来。结果表明，PGM 还通过疏水相互作用促进 BLG 的结构展开及其与 PGM 的结合，特别是在酸性 pH 下，这一结果通过外源荧光光谱法得到进一步证实。在 pH 3 时，疏水相互作用被认为是 BLG 与 PGM 之间的主要相互作用机制，而静电相互作用则是 BLG 与 BSM 之间的主要相互作用机制。
