Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada, T6G 2P5.
Food Chem. 2012 Dec 15;135(4):2245-52. doi: 10.1016/j.foodchem.2012.07.071. Epub 2012 Jul 25.
High pressure processing of ovotransferrin was carried out to study the structural and physiochemical changes of ovotransferrin under various pressure levels. At pH 8 and pressures higher than 200 MPa, a decrease in total sulfhydryl groups and an increase in surface hydrophobicity were observed along with a partial aggregation. A gradual shift of denaturation peak towards higher temperature was noticed up to 500 MPa, leading to a total loss of the enthalpy of denaturation at pressures of 600 and 700 MPa, where a significant decrease in intrinsic fluorescence was also observed. At pH 3, the ovotransferrin adopted a molten globule state, associated with a significant increase in surface hydrophobicity and reactive sulfhydryl content; structurally, no clear denaturation peaks in differential scanning calorimetry (DSC) were detected at any level of pressure treatment whereas a noticeable decrease in intrinsic fluorescence was evidenced up to 600 MPa and then increased at 700 MPa pressure treatment. Fourier transform infrared spectroscopy (FT-IR) revealed that the conformational structure were changed from helices, sheets, turns, and aggregated strand to mostly intermolecular β-sheets or aggregated strands at pH 8 at 200 MPa but switched back to original structure at higher pressures.
高压处理卵转铁蛋白，研究不同压力水平下卵转铁蛋白的结构和物理化学变化。在 pH8 和压力高于 200MPa 的条件下，总巯基数量减少，表面疏水性增加，同时发生部分聚集。在 500MPa 时，变性峰逐渐向高温移动，导致 600 和 700MPa 时变性焓完全丧失，同时也观察到内源荧光显著降低。在 pH3 时，卵转铁蛋白呈无定形球蛋白状态，表面疏水性和反应性巯基含量显著增加；结构上，在任何压力处理水平下，差示扫描量热法（DSC）都没有检测到明显的变性峰，而在 600MPa 时，内源荧光显著降低，然后在 700MPa 时增加。傅里叶变换红外光谱（FT-IR）表明，在 pH8 下，在 200MPa 时卵转铁蛋白的构象结构从螺旋、片层、转角和聚集链转变为主要的分子间β-折叠或聚集链，但在较高压力下又恢复到原始结构。
