用拉曼光谱分析低压均质处理对大豆分离蛋白结构的影响

本文测定了不同均质处理条件下大豆分离蛋白溶液的拉曼光谱和圆二色谱，以此来研究低压均质对大豆分离蛋白结构的影响。研究表明：均质压力较低（0~8 MPa）时，大豆分离蛋白的二级结构基本保持不变；当均质压力为10~30 MPa时，α-螺旋和无规则卷曲结构明显增加，β折叠显著降低，色氨酸残基和酪氨酸残基由“埋藏态”逐渐转变为“暴露态”，蛋白质分子表现出解聚的行为；均质压力继续增大到40 MPa过程中，酪氨酸费米共振线I850/I830比值略有下降，酪氨酸残基由“暴露态”向“埋藏态”转变，表明产生了蛋白聚集体，并且低压均质处理未显著改变二硫键的构型。综上可知，拉曼光谱通过对蛋白分子的二级结构和三级结构进行表征，揭露了低压均质处理使得大豆分离蛋白表现出先解聚后聚合的性质，并且圆二色谱的结果验证了上述结论。
In this study, Raman spectroscopy and circular dichroism spectra of soy protein isolate solutions subjected to different homogenization conditions were acquired for investigations on the effects of low pressure homogenization on the structure of soy protein isolate. The results showed that the secondary structure of soybean protein isolate basically remained unchanged when the homogenization pressure was low (0~8 MPa). When the homogeneous pressure was 10~30 MPa, the α-helical and random coil structures increased significantly, β-sheet decreased significantly. Thetryptophan and tyrosine residues gradually changed from “buried state” to “exposed state”, and the protein molecule exhibited depolymerization behavior; Over the course of the increase of homogenization pressure to 40 MPa, the ratio of tyrosine - Fermi resonance line I850/I830 decreased slightly, and the tyrosine residue changed from “exposed state” to “buried state”, indicating that protein aggregates were produced, and low pressure homogenizatio did not significantly alter the configuration of disulfide bonds. In summary, the secondary structure and tertiary structure of protein molecules can be characterized by Raman spectroscopy, and obtained results revealed that low-pressure homogenization induced depolymerization and then polymerization of soy protein isolate. These results were confirmed by circular dichroism.