光谱学与光谱分析, 2012, 32 (4): 1061, 网络出版: 2012-04-16   

咖啡酸与乳蛋白结合的光谱特性及结合物抗氧化活性变化

Spectral Properties of Interaction between Caffeic Acid and Milk Protein and The Change in Antioxidant Capacity
作者单位
1 中国农业大学教育部功能乳品重点实验室, 北京100083
2 畜产品北京市高等学校工程研究中心, 北京100083
3 中粮集团有限公司, 北京100020
4 University of Alberta, Edmonton, Alberta, Canada
摘要
利用紫外光谱和荧光光谱技术评价了咖啡酸与乳蛋白(α-酪蛋白、 β-酪蛋白、 κ-酪蛋白、 α-乳白蛋白、 β-乳球蛋白)两者结合的结合常数、 结合作用力、 结合距离以及能量转移效率, 通过二苯代苦味酰基(DPPH)自由基清除率和铁离子还原能力(FRAP)对两者结合导致的抗氧化活性变化进行了测定。 结果表明咖啡酸会使乳蛋白发生内源性荧光猝灭。 吉布斯自由能变ΔG<0, 表明反应是自发进行的。 其中咖啡酸与α-酪蛋白之间以静电引力结合(ΔH<0, ΔS>0), 与β-酪蛋白、 α-乳白蛋白的结合作用力为氢键(ΔH<0, ΔS<0), 与κ-酪蛋白、 β-乳球蛋白是以疏水作用力结合(ΔH>0, ΔS>0)。 两者结合距离r0<7 nm, 符合非辐射能量转移条件, 证明咖啡酸对乳蛋白的荧光猝灭是由于生成不发光的配合物而引起的静态猝灭。 此外, 两者结合导致咖啡酸的抗氧化能力受到不同程度的抑制。
Abstract
The interaction between caffeic acid and milk protein (α-casein, β-casein, κ-casein, α-lactalbumin, β-lactoglobulin) were studied in this work. The binding constant KA, binding force, binding distance r0 and transfer efficiency E were evaluated by UV-absorption and fluorescence spectroscopy. The antioxidant capacity of the combination was determined using both 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and ferric reducing antioxidant power (FRAP) assay. The results showed that the interaction between milk protein and caffeic acid resulted in the endogenous fluorescence quenching of milk protein, which belongs to a static quenching mechanism. The negative sign of free energy meant that the interaction process was spontaneous. The strength between caffeic acid and α-casein was electrostatic attraction (ΔH<0, ΔS>0), and that between β-casein and α-Lactalbumin was hydrogen bonding (ΔH<0, ΔS<0). In addition, the strength of caffeic acid interacting with κ-casein and β-lactoglobulin was hydrophobic interaction (ΔH>0, ΔS>0). The binding distance (r0<7 nm) proved that caffeic acid lead to a static quenching mechanism of milk protein. The antioxidant capacity of caffeic acid was inhibited by milk protein to different degrees.

余丹丹, 张昊, 丁庆波, 郭慧媛, 吴建平, 张录达, 任发政. 咖啡酸与乳蛋白结合的光谱特性及结合物抗氧化活性变化[J]. 光谱学与光谱分析, 2012, 32(4): 1061. YU Dan-dan, ZHANG Hao, DING Qing-bo, GUO Hui-yuan, WU Jian-ping, ZHANG Lu-da, REN Fa-zheng. Spectral Properties of Interaction between Caffeic Acid and Milk Protein and The Change in Antioxidant Capacity[J]. Spectroscopy and Spectral Analysis, 2012, 32(4): 1061.

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