利用内源性荧光光谱、 荧光探针(ANS)结合荧光光谱及圆二色谱, 以乳白蛋白-油酸为参照, 研究了乳白蛋白结合亚油酸后, 疏水性氨基酸、 疏水性区域、 三级结构及二级结构的变化, 并利用亚甲基蓝的方法评价了该复合物的抗肿瘤活性。 荧光光谱结果显示, 与乳白蛋白-油酸复合物类似, 乳白蛋白结合亚油酸后, 其内源性荧光光谱显著红移, 从331.07 nm移至337.60 nm; 外源性ANS结合光谱蓝移, 从516.20 nm移至508.50 nm; 且荧光强度增加, 表明乳白蛋白结合亚油酸后同样出现了疏水性氨基酸及疏水性区域暴露的现象。 圆二色谱结果表明, 与乳白蛋白-油酸复合物类似, 乳白蛋白结合亚油酸后, 三级结构部分丧失, 二级结构中β-转角及无规卷曲的含量显著降低, β-折叠含量增加。 细胞实验证实了乳白蛋白-亚油酸复合物具有良好的抗肿瘤效果。 该研究从复合物结构和功能的两方面, 为新型抗肿瘤乳白蛋白-亚油酸复合物的开发提供了依据。

The structure changes of α-lactalbumin after binding oleic acid and linoleic acid, including hydrophobic amino acids, hydrophobic regions, tertiary structure, secondary structure, was studied by intrinsic fluorescence, ANS-binding intrinsic fluorescence and circular dichroism spectrum, respectively. The anti-tumor activity of the lactalbumin-oleic acid complex and lactalbumin-linoleic acid complex was measured using the methylene blue method. It can be seen from the fluorescence spectra that a significant red-shift from 331.07 to 337.67 nm and 337.60 nm of α-lactalbumin occurred after binding of oleic acid and linoleic acid, respectively. Together with the ANS-binding spectra, which exhibited a blue-shift (from 516.20 to 514.10 nm and 508.50 nm, respectively) with an increased fluorescence intensity, it can be indicated that binding of oleic acid and linoleic acid lead to the exposure of hydrophobic amino acids and hydrophobic regions. Results of circular dichroism spectra indicated the partial loss of the tertiary structure, and an decrease of β-turn and random coil, which turn to the β-sheet structure. Furthermore, the anti-tumor activity of the two complexes was verified on the three types of tumor cells. This study laid a theoretical basis for the development of anti-tumor drugs.