School of Food Science and Technology, Henan Institute of Science and Technology, Xinxiang, Henan 453003, PR China.
School of Food Science and Technology, Henan Institute of Science and Technology, Xinxiang, Henan 453003, PR China.
Food Res Int. 2020 Jun;132:109111. doi: 10.1016/j.foodres.2020.109111. Epub 2020 Feb 19.
Biopolymer complexes fabricated by proteins and neutral polysaccharides may have some specific or innovative functionalities. However, only little is known about the structural characteristics and molecular interaction mechanisms of proteins-neutral polysaccharides biopolymer complexes. Understanding these informations is of major interest for the design of new proteins-polysaccharides biopolymer complexes with specific and/or innovative functionalities. Thus, the aim of the present study was to investigate the structural characteristics and molecular interaction mechanisms of lactoferrin (LF) and oat β-glucan (OG) with and without heat treatment at different OG concentrations (0.2, 0.5 and 0.9%, w/v). Isothermal titration calorimetry (ITC) results showed that LF and OG could interact with each other. The binding behavior between LF and OG at 25 °C was a spontaneous process, and electrostatic interactions, hydrogen bonding and van der Waals forces contributed to the LF-OG self-assembling behavior. OG concentration influenced the thermodynamic characterization of interactions between LF and OG. LF was susceptible to aggregation and thermal denaturation in the presence of OG. The increased turbidity and particle size of LF-OG complexes suggested the formation of large complexes in aqueous solution. SEM results showed that LF-OG self-assembles exhibited physically cross-linked networks at low OG concentration, while formed some spherical complexes at high OG concentration; LF-OG thermally modified complexes exhibited the honeycomb-like structures with different particle sizes in a concentration-dependent manner. Fluorescence spectroscopy results indicated that OG can change the structure of LF, leading to the exposure of Trp residues of LF molecules toward a more polar microenvironment. Raman difference spectra and circular dichroism revealed that the addition of OG could alter the secondary structure of LF, and the most noticeable changes were in the regions connected β-structures. The apparent viscosity of LF-OG complexes were higher than that of LF or OG alone, indicating that there was synergism between LF and OG. Overall, the self-assembling complexes and thermal complexes of LF and OG can be formed at 25 °C and 90 °C, respectively. These formed LF-OG nanocomplexes and microcomplexes (both the self-assembling and thermal complexes) with unique structures can be widely used in food, pharmaceutical and cosmetic industries, which will be suitable for encapsulation and transportation of bioactive compounds, or as fat substitutes.
由蛋白质和中性多糖制成的生物聚合物复合物可能具有一些特殊或创新的功能。然而，人们对蛋白质-中性多糖生物聚合物复合物的结构特征和分子相互作用机制知之甚少。了解这些信息对于设计具有特定和/或创新功能的新型蛋白质-多糖生物聚合物复合物具有重要意义。因此，本研究旨在研究乳铁蛋白（LF）和燕麦β-葡聚糖（OG）在不同 OG 浓度（0.2、0.5 和 0.9%，w/v）下的结构特征和分子相互作用机制，有无热处理。等温滴定量热法（ITC）结果表明 LF 和 OG 可以相互作用。25°C 时 LF 和 OG 之间的结合行为是一个自发过程，静电相互作用、氢键和范德华力有助于 LF-OG 自组装行为。OG 浓度影响 LF 和 OG 之间相互作用的热力学特征。在 OG 的存在下，LF 容易聚集和热变性。LF-OG 复合物的浊度和粒径增加表明在水溶液中形成了大复合物。SEM 结果表明，LF-OG 自组装在低 OG 浓度下表现出物理交联网络，而在高 OG 浓度下形成一些球形复合物；LF-OG 热改性复合物以浓度依赖的方式表现出具有不同粒径的蜂窝状结构。荧光光谱结果表明，OG 可以改变 LF 的结构，导致 LF 分子的色氨酸残基暴露于更极性的微环境中。拉曼差谱和圆二色性表明，OG 的加入可以改变 LF 的二级结构，最明显的变化发生在连接β-结构的区域。LF-OG 复合物的表观粘度高于 LF 或 OG 单独的表观粘度，表明 LF 和 OG 之间存在协同作用。总的来说，LF 和 OG 可以在 25°C 和 90°C 下分别形成自组装复合物和热复合物。这些形成的 LF-OG 纳米复合物和微复合物（自组装和热复合物）具有独特的结构，可以广泛应用于食品、制药和化妆品行业，适合封装和运输生物活性化合物，或作为脂肪替代品。
