亚麻籽蛋白酶解肽抑制胆固醇吸收的生物学功效及其机制的研究

As a distinguished plant oil resource in Inner Mongolia, flaxseed rich in fat and also protein, regarded as high-quality plant protein resource. Currently, it is mainly used for pressing oil, however, a large number of protein which contained in greaves left from exploiting the oil can’t be utilized fully, resulting in resource waste. In the present study, in order to utilize flaxseed protein resource efficiently, we will study the degradation product which digested from flaxseed protein-inhibitory effect of flaxseed peptide on cholesterol micelle solubility, and analyze the characterization of composition and molecular structure of hypocholesterolemic peptide. Furthermore, detect the effect of flaxseed peptides on serum cholesterol content and activity of cholesterol absorption of related enzymes in liver of fat rat, clear the biological efficacy and possible mechanism on lowering cholesterol in blood serum. Clear the effect of flaxseed peptides on absorption level of cholesterol in intestinal cells, cholesterol absorption related gene mRNA, and expression level of protein. Reveal the mechanism of reducing the absorption of serum cholesterol in the intestinal tract. To clarify the nutritional quality and utilization of flaxseed peptides on lowering cholesterol in blood serum.

亚麻籽是内蒙古的优势特色植物油料资源，脂肪含量高，还含有丰富的蛋白质，也是优质的植物蛋白资源。目前其主要用于压榨制油，但榨油后的饼中含有的大量蛋白质未被充分利用，造成资源浪费。为此，本研究以高效利用亚麻籽蛋白为目的，研究亚麻籽蛋白消化后的降解产物-肽对抑制胆固醇胶束溶解的效果及结构表征，明确其氨基酸序列即一级结构；探测亚麻籽肽对大鼠血清胆固醇含量及肝脏中胆固醇吸收相关酶活性等的影响，明确其降低血清胆固醇含量的生物学功效及可能机制；考察亚麻籽肽对肠道细胞胆固醇吸收水平、胆固醇吸收相关基因mRNA和蛋白质的表达水平的影响，揭示其降低肠道胆固醇吸收的机制，阐明亚麻籽肽在降低机体血清胆固醇方面的营养品质和利用途径。

本课题以高效利用内蒙古的优势特色植物蛋白资源亚麻籽蛋白为目的，主要研究了亚麻籽蛋白消化后的降解产物-肽是否具有降胆固醇作用，其结构特点是什么，发挥降胆固醇作用的机制如何等问题。通过本课题研究首先鉴定出6种胆固醇胶束溶解度抑制率较高的亚麻籽肽，其氨基酸序列即一级结构分别为IIPAF、LNFF、LLGTL、IIF、IPPF、LLGA，其特点：疏水性大于10的氨基酸如脯氨酸、异亮氨酸、苯丙氨酸含量高；采用Western blot和Dot blot分析结果证明获得的亚麻籽肽IPPF的确来源于亚麻籽蛋白，并且亚麻籽蛋白酶解物的胆固醇胶束溶解度抑制率越高其相对含量越高；探讨了亚麻籽肽对高脂血症小鼠的降脂作用，发现对高脂血症小鼠血脂异常现象具有缓解作用，降低动脉硬化程度, 有效提高血清中HDL-C的水平，且对小鼠脾脏有一定的改善作用，对肝脏细胞的脂肪变性有较好的修复作用，说明亚麻籽肽能够显著降低机体血脂水平，进一步研究证实亚麻籽肽是通过调节机体能量代谢、氨基酸代谢和脂质代谢起到了降血脂作用。本课题阐明了亚麻籽蛋白降解物降低血清胆固醇的营养品质，为亚麻籽蛋白深加工利用提供了科学理论依据。