对酰化大米蛋白的溶解度、表面电荷情况及二级结构等理化特性进行初步探讨，同时研究了酰化大米蛋白胰蛋白酶酶解特性。结果表明，大米蛋白等电点随着酰化程度的增大，越来越向酸性方向迁移，由原来的4.8分别迁移到4.4、3.8、3.3。酰化能够改善大米蛋白的溶解性，从0.4 mg/mL提高到了0.7 mg/mL（中性pH）。酰化能够明显增加蛋白质表面的净负电荷，酰化程度越大，净负电荷增加越多。酰化对大米蛋白的二级结构也有一定的影响，α-螺旋和无规卷曲含量基本不变，β-折叠含量下降，β-转角的含量上升。酰化可以提高大米蛋白胰蛋白酶酶解速率和消化率，相同底物浓度时动力学参数a随着酰化度的增大而增大。酶解物电泳表明，胰蛋白酶酶解120 min后，未改性大米蛋白酶解物在20 kDa、16.9 kDa和14 kDa处仍有清晰可见的条带，改性大米蛋白酶解物则这些条带几乎都完全消失。

The physicochemical properties of acetylated rice protein, including solubility, surface charge, and secondary structure, were explored; the enzymatic hydrolysis of acetylated rice protein by trypsin was also investigated. The results showed that the isoelectric point (pI) of acetylated rice protein was decreased with increasing degrees of acetylation. Acetylation improved the solubility of rice protein, as it was increased to 0.7 mg/mL from 0.4 mg/mL (neutral pH) upon acetylation. Acetylation significantly increased the net negative surface charge of the protein, and a higher degree of acetylation led to an increased net negative charge. Meanwhile, acetylation also had certain effects on the secondary structure of rice protein. The α-helix and random coil contents remained the same, while the β-sheet content decreased and β-corner content increased upon acetylation. Acetylation enhanced the enzymatic hydrolysis rate and digestibility of rice protein by trypsin. When the substrate concentration was the same, the kinetic parameter increased with increasing degree of acylation. The electrophoresis results of the enzymatic hydrolysates showed that after enzymatic hydrolysis by trypsin for 120 min, bands at 20 kDa, 16.9 kDa, and 14 kDa were still clearly visible for the unmodified rice protein, while the bands corresponding to the acetylated rice protein almost completely disappeared.

国家“十二五”科技攻关项目（2012BAD37B08-3）；863计划（2013AA102203-7）;国家科技支撑计划项目（2006BAD27B09；2006BAD04A12）