壳寡糖酶法糖基化修饰对玉米醇溶蛋白功能性质的影响

为了提高玉米醇溶蛋白的生物利用率,以微生物转谷氨酰胺酶为催化剂,壳寡糖(分子质量为1 500 Da)作为酰基受体,通过糖基化反应修饰玉米醇溶蛋白,分析糖基化修饰对玉米醇溶蛋白物化性质和抗氧化活性的影响。红外光谱和游离氨基含量的测定结果表明,在转谷氨酰胺酶的催化下,玉米醇溶蛋白与壳寡糖发生了共价结合。与玉米醇溶蛋白和交联玉米醇溶蛋白相比,糖基化玉米醇溶蛋白的表面疏水性显著降低,表明其水溶性显著改善;糖基化玉米醇溶蛋白的抗氧化活性(包括1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基、超氧阴离子自由基和羟自由基清除活性,还原力和亚铁离子螯合能力)显著提高,尤其是DPPH自由基清除活性,其EC50值为0.945 mg/m L;糖基化玉米醇溶蛋白的持水性、吸油性、乳化性和Zeta电位的绝对值均显著降低。实验结果可为糖基化玉米醇溶蛋白在食品工业的应用提供参考。

Effect of Transglutaminase-Catalyzed Glycosylation with Chitosan on the Functional Properties of Zein

The present work aimed to improve the bioavailability of zein. We employed microbial transglutaminase as a biocatalyst, and chitosan with a molecular mass of 1 500 Da as an acyl acceptor to modify zein by glycosylation reaction. The functional properties of glycosylated zein were studied in comparison with its intact and cross-linked counterparts. The results of Fourier transform infrared (FT-IR) spectroscopy and free amino group content indicated that chitosan was covalently conjugated to zein under the catalysis of transglutaminase. The surface hydrophobicity of glycosylated zein was decreased significantly compared with that of the original and cross-linked ones, suggesting a significant improvement in the water solubility of zein. Meanwhile, antioxidant activities, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion and hydroxyl radical scavenging activities, reducing power and Fe2+-chelating capacity of glycosylated zein were increased significantly, and its EC50 value for DPPH radical scavenging activity was 0.945 mg/mL. Water-binding capacity, oil-binding capacity, emulsifying properties and the absolute value of Zeta potential of glycosylated zein were decreased significantly. These results can provide a basis for the application of glycosylated zein in the food industry.