天然和热变性乳铁蛋白与姜黄素复合物的结构表征及结合机理研究

Structural Characteristics and Binding Mechanism of Native and Thermally Modified Lactoferrin-curcumin Complexes

为了解决姜黄素溶解性较差的问题,运用浊度法、动态光散射、红外光谱、圆二色谱和荧光光谱研究了热变性前后乳铁蛋白(LF)与姜黄素(Cur)复合物的结构特性和结合机制。结果表明,LF-Cur复合物的浊度和粒径与LF结构和Cur浓度密切相关。当Cur浓度为1.4×10^-5~5.4×10^-5mol/L时,天然LF-Cur复合物为纳米颗粒,溶液浊度低;当Cur浓度为8.1×10^-5~1.08×10^-4mol/L时,天然LF-Cur复合物为亚微米颗粒,溶液浊度高。热变性LF-Cur复合物均为纳米颗粒。随着Cur浓度的增加,LF-Cur复合物的ζ-电位增加,有利于提高复合物溶液的稳定性。圆二色光谱分析表明,热变性使得LF的二级结构发生了不可逆的改变,Cur的添加能够改变天然和热变性LF的二级结构。红外光谱分析表明,氢键参与了LF与Cur的结合。荧光光谱结果表明,Cur与天然和热变性LF的结合均为静态淬灭过程,且热变性LF与Cur的结合能力较强。热变性能够提高LF对Cur的包埋率,为开发基于LF为载体运载疏水性多酚提供了理论依据。

The structural characteristics and binding mechanism of native and thermally modified lactoferrin( LF) and curcumin( Cur) were investigated by turbidimetry,dynamic light scattering,infrared spectra,circular dichroism and fluorescence spectrain to solve the problem of poor aqueous solubility of Cur.The results showed that turbidity and particle size of LF-Cur complexes were closely related to the structure of LF and concentration of Cur.Native LF-Cur complexes were nanoparticles at the Cur concentration of 1.4 × 10-5~ 5.4 × 10-5 mol/L with the low-level turbidity and submicremeter particles at the Cur concentration of 8.1 × 10-5~1.08 × 10-4 mol/L with the high-level turbidity. Thermally modified LF-Cur complexes were all nanoparticles.The ζ-potential of LF-Cur complexes was increased by the increasing of Cur concentration. Far-UV circular dichroism results indicated that heat denaturation might irreversibly alter the secondary structure of LF. The addition of Cur might alter the secondary structure of native and thermally modified LF. Analysis of infrared spectra results showed that Cur could bind to LF through the hydrogen bond.Fluorescence spectra results indicated that the combination of Cur with native and thermally modified LF was a static quenching process and thermally modified LF exhibited a strong affinity for Cur. Thermal denaturation could improve the encapsulation efficiency of LF to Cur. These results could provide a theoretical basis for the development of LF as a carrier of hydrophobic polyphenols.