米糠中游离和结合态脂肪酶的分布、结构和活性的研究

我国每年米糠非常大，米糠含油约20%，米糠油富含维生素E、甾醇、谷维素等营养物质，营养价值极高。但米糠利用效率极低，仅10%进行深度加工，主要是米糠中脂肪酶快速使米糠酸败，米糠稳态化是米糠高值化利用的瓶颈技术。然而，人们对米糠脂肪酶在米粒中分布及其活性的研究甚少。因此本项目拟通过多种染色、激光共聚焦显微镜及糙米分层碾削技术探究米糠脂肪酶在米粒结构和糠中的分布；针对不同形态脂肪酶生化特点，采用层析、柱分离和电泳技术进行分离纯化，获得不同结合态的酶；利用质谱和圆二色谱等现代仪器分析技术表征不同结合态米糠脂肪酶的结构特点；通过分子模拟技术和活性中心氨基酸的修饰技术探讨不同结合态脂肪酶的催化活性中心的结构、活性，了解其催化机理和影响其活性的影响因素，为寻找钝化米糠脂肪酶的方法，探索绿色、快速、有效、低成本的米糠稳态化技术提供科学依据。

In our country，the annual production of rice bran is high, but the utilization rate is extremely low, only 10% is used for further processing. Rice bran contains about 20% oil. Rice bran oil is rich in vitamin E, sterol, oryzanol and other nutriments which are good for our health. But the further processing of rice bran is impeded because of the rancidity caused by lipase. However, there is little research on the distribution and activity of rice bran lipase in rice grain. Therefore, this study is designed to explore the distribution of rice bran lipase in rice structure and bran structure by using staining techniques, laser confocal microscope and brown rice layered milling technology. Chromatography, column separation and electrophoretic technology were used to separate and purify the lipase according to the biochemical characteristics of different forms of lipase. The structures of different lipase were analyzed by using mass spectrometry and circular dichroism spectrum. Molecular simulation techniques and modification of amino acids in the active center were used to study the structures and activities of the different forms of lipase in order to know the catalytic mechanisms, influence factors of its activity which can be used to stabilize rice bran in an effective and low cost way.