蛋白质谷氨酰胺酶对米谷蛋白的分子结构及功能性质的影响

Effects of Protein-Glutaminase on the Molecular Structure and Functional Properties of Rice Glutelin

目的:研究蛋白质谷氨酰胺酶(PG酶)对米谷蛋白的分子结构及功能性质的影响。方法:采用zeta电位仪、体积排阻色谱(SEC-HPLC)及傅里叶红外光谱(FT-IR)研究米谷蛋白及其酶法脱酰胺样品的zeta电位、相对分子质量分布和二级结构变化。研究不同pH值条件下酶法脱酰胺样品溶解度的变化。结果:随着酶解时间的延长,米谷蛋白的脱酰胺度逐渐增大,当反应时间48 h时,DD值为52.29%;zeta电位逐渐增加,体系中蛋白质聚合体部分逐渐减少,α-螺旋结构有所降低;米谷蛋白在中性溶液中溶解度显著提高(达96.99%)。结论:酶法脱酰胺使蛋白质分子所带负电荷增加,分子间静电排斥作用增大;在中性pH条件下米谷蛋白的溶解度上升。

Objective： To study the effects of protein glutaminase on the molecular structure and functional properties of rice glutelin. Methods： The effects of enzymolysis time on the deamidation degree value （DD） were studied; Zeta potential instrument, SEC-HPLC and FT-IR were used to study the changes of zeta potential, molecular weight distribution and secondary structure; the solubility changes of deamidizing sample at different pH values were also measured. Results： The DD of rice glutezlih was gradually increased with the enzyme treated time, which increased to 52.29% when treated by enzyme for 48 h; zeta potential increased gradually while protein aggregate fractions of decreased, and or-helix structure reduced; solubility in neutral solution increased significantly （up to 96.99%）. Conclusions： Protein glutaminase increased the intermolecular repulsion between molecules because the deamidation of rice glutelin induced the increase of negative charge, thereby increasing the solubility at neutral pH.