大豆蛋白-黄芩素的结合机制及蛋白构象和功能变化

探索大豆蛋白组分中β-伴大豆蛋白(7S)/大豆蛋白(11S)与黄芩素的结合机制,考察复合物构象及功能特性的变化。傅里叶变换红外光谱表明黄芩素诱导蛋白的β-折叠转化为α-螺旋和无规卷曲。内源荧光光谱证实了黄芩素的加入使7S、11S结构变得更紧密。黄芩素与蛋白的反应自发进行,并通过静态方式猝灭蛋白荧光。7S、11S蛋白分别通过氢键和疏水相互作用与黄芩素结合。分子对接结果表明,黄芩素对11S的亲和力高于7S。扫描电子显微镜显示了7S、11S与复合物的微观结构差异。此外,与黄芩素结合后,7S、11S的表面疏水性下降,热稳定性及其他功能特性提升。

伴大豆球蛋白水解肽的制备及其对沙门氏菌增殖的影响

利用等电沉淀和盐析的方法,获得大豆球蛋白,并通过Sepharose-CL-6B凝胶柱层析分离纯化,得到单一组分,经SDS-PAGE鉴定为纯化的7 S伴大豆球蛋白,然后将其用胃蛋白酶水解得到伴大豆蛋白水解肽(PTC)。通过96孔细胞培养板2倍稀释法,对不同浓度的伴大豆球蛋白胃蛋白酶水解肽(6,3,1.5和0.75 mg/mL)与沙门氏杆菌共同培养,观察了伴大豆蛋白水解肽对沙门氏杆菌增殖的影响。结果发现,添加不同浓度的伴大豆蛋白水解肽可以影响沙门氏菌的增殖,其中6 mg/mL和3 mg/mL的PTC对沙门氏菌的生长产生明显的抑制作用,1.5 mg/mL的PTC对沙门氏菌作用不明显,而0.75 mg/mL的PTC有微弱的促进作用,表现一定的营养作用。

Effect of Acid Treatment on Interfacial and Foam Properties of Soy Proteins

The goal of the present work was to study the effects of acid treatment on the foaming properties of a soybean protein isolate （SPI） and its fractions, glycinin （11S） and β-conglycinin （7S）. The structural characteristics, interfacial properties, foaming capacity and stability of the treated proteins were studied. Results from surface hydrophobicity and differential scanning calorimetry （DSC） showed that the acid treatment caused the complete denaturation of 11S and a partial denaturation of 7S. This protein unfolding affected their interracial properties, which led to an improvement in the foaming properties of both protein fractions and isolate. Treated 7S showed the best behavior in the rearrangement process, probably due to its smaller size and its modified structural characteristics. All treated proteins showed stronger interracial films. The foams of treated proteins were destabilized mostly due to gravitational drainage rather than Ostwald ripening.