脂肪氧合酶催化亚油酸氧化与大豆蛋白相互作用的荧光光谱分析

Fluorescence Assay of Interaction of Soybean Protein and Linoleic Acid Oxidation Induced by Lipoxygenase

利用低脂质含量大豆蛋白、脂肪氧合酶和亚油酸组成的三元体系,模拟大豆蛋白质制备过程,通过荧光光谱结合可溶性蛋白表面疏水性分析,研究了反应后大豆蛋白芳族氨基酸的氧化情况,结果证明,在LOX的催化作用下,LA过氧化所产生的氢过氧化物及其降解产物可与大豆蛋白作用,反应后大豆蛋白的荧光光谱最大激发波长在350nm,最大发射波长在440nm。LOX催化LA氧化与大豆蛋白的相互作用,在LRSP+LA+LOX模拟体系中产生荧光物质。该荧光物质部分可溶于氯仿-甲醇溶液的有机相中,其荧光光谱最大激发波长在350nm,最大发射波长在430nm,且荧光强度随着反应程度的增加而增强。伴随着荧光物质的形成,反应后大豆蛋白的可溶性蛋白的表面疏水性降低。使用抗氧化剂(BHT)可抑制荧光物质的产生和蛋白质疏水性的丧失。

Soybean proteins were prepared from the model systems consisting of lipid-reduced soybean proteins and different levels of linoleic acid（LA） and lipoxygenase. The interactions of soybean proteins and oxidizing linoleic acid catalyzed by lipoxygenase were assayed by fluorescence spectroscopy and soluble protein hydrophobicity. The fluorescence of the oxidized samples showed excitation and emission maxima at 350nm and 440 nm respectively. The fluorescent compounds were partially soluble in the organic layer of the chloroform-methanol （2：1,V/V）. The solution fluorescence showed an excitation maximum at 350 nm and an emission maximum at 430 nm, and the intensity increased with reaction time. The interactions of soybean proteins and oxidizing linoleic acid catalyzed by lipoxygenase also resulted in decreases of soluble protein hydrophobicity. With an antioxidant （BHT） addition, the changes in fluorescence and soluble protein hydrophobicity were inhibited.