不同酶切方式引发大豆蛋白构象变化及功能特性评价

Evaluation on Changes and Functional Properties of Soy Protein Conformation due to Different Enzymolysis Methods

本研究以枯草杆菌碱性蛋白酶、菠萝蛋白酶、枯草杆菌中性蛋白酶、胃蛋白酶和胰蛋白酶酶解大豆分离蛋白产物为研究对象,借助十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、紫外吸收光谱、荧光光谱、红外光谱解析不同酶切条件下蛋白产物构象变化,并对其乳化性及抗氧化活性等功能特性进行评价。结果表明:酶解促进蛋白解折叠,内部氨基酸暴露,并受到酶切方式的影响;菠萝蛋白酶酶解作用范围宽泛,疏水性氨基酸浓度达到最大值(27.10±0.08)%,氨基酸存在微环境发生改变,形成柔性结构单元,其乳化性及抗氧化性都得到明显改善,为具有最佳功能特性的酶解蛋白;酶特异性作用位点导致酶解作用程度较低的枯草杆菌碱性蛋白酶、枯草杆菌中性蛋白酶、胃蛋白酶及胰蛋白酶水解产物功能特性均高于未处理样品。另外,研究还发现,水解程度最低的胰蛋白酶水解产物呈现优异乳化稳定性,这是因为大豆中胰蛋白酶抑制剂抑制蛋白过度水解,提升蛋白溶解度同时,肽段长度适宜稳定包裹油滴。

In the present study,the hydrolysates of soy protein isolate prepared by bacillus subtilis alkaline protease,bromelain,bacillus subtilis neutral protease,pepsin and trypsin were used as the research objects.Conformational changes of soybean protein hydrolysates prepared by different enzymolysis manners were analyzed by means of sodium lauryl sulfate-polyacrylamide gel electrophoresis and ultraviolet absorption spectroscopy,Fluorescence spectroscopy and Fourier transform infrared spectrum.Finally,the emulsification and antioxidant activity of the hydrolysates were evaluated in the present paper.The results indicated that enzymatic hydrolysis promoted protein unfolding,exposed internal amino acids,and it was affected by the way of enzymatic cleavage.Bromelain enzymatic hydrolysis hada wide range of hydrolysis,the concentration of hydrophobic amino acids reached the maximum value of(27.10±0.08)%,and the microenvironment of amino acids was changed,forming a flexible structural unit,and its emulsification and antioxidant properties have been significantly improved.It was an enzymatic protein with the best functional properties.The functional properties of subtilis alkaline protease,bacillus subtilis neutral protease,pepsin and trypsin hydrolysate,which had a low degree of enzymolysis due to the specific action site of the enzyme,werehigher than those of untreated sample.In addition,the study also found that the trypsin hydrolysate with the lowest degree of hydrolysis exhibits excellent emulsification stability.This was because trypsin inhibitors in soybeans inhibit excessive protein hydrolysis and improve protein solubility.At the same time,the peptide length was suitable for the stable coating of oil droplets.