摘要小麦是我国最主要的粮食作物之一，而麦胚是小麦籽粒的核心，富含丰富的优 质蛋白，但我国目前利用效率比较低。麦胚蛋白通过酶水解可生成具有降血糖活性 的氨基酸序列，即降血糖肽。本文研究的是通过光谱法研究超声预处理和酶解过程 中蛋白质二级结构的变化。本文利用超声辅助酶法制备麦胚降血糖肽，并通过超滤、 732 离子交换树脂、葡聚糖凝胶层析进行分离纯化麦胚降糖肽并对其进行结构表征。81707

为了探索蛋白质二级结构在超声波预处理和酶解过程中的变化情况，本文使用 荧光光谱、近红外拉曼光谱和傅里叶变换红外光谱对蛋白质结构进行分析。在超声 预处理过程中，超声波使得蛋白质二级结构朝着固定的趋势变化，并在最优超声时 间点达到最明显的变化；在酶解过程中，由于蛋白质分子不断被胰蛋白酶水解，蛋 白质二级结构也不断变化，因此其变化的规律不如超声过程明显。

本文使用小型超滤系统、732 阳离子交换树脂和葡聚糖凝胶层析等对超声辅助 酶解制备的麦胚蛋白进行进一步分离纯化。Sephadex-G15 分离所得第一个峰(记作 C-II-2。1)的活性最好，利用这部分分离所得再经过 HPLC 分离，选择其活性最高和 含量最高的峰单独收集，进行液质联用分析结构表征，多肽序列 m/z=274。4，氨基 酸序列可能是 Thr-Gly-Pro、Gly-Thr-Pro、Ser-Pro-Ala、Pro-Ser-Ala、Ile -Ala-Ala、 Leu-Ala-Ala；多肽序列 m/z=246。53 氨基酸序列可能是 Arg-Ala、Asn-Ile、Asn-Leu、 Lys-Val、Gln-Val、Gly-Ile-Gly、Gly-Leu-Gly；多肽序列 m/z=388。67 氨基酸序列可 能是 Gly-Arg-Arg、Arg-Arg-Gly。

分子量＜5kDa 的多肽对四氧嘧啶高血糖小鼠的试验结果表明，多肽 48。6mg/kg 进 行 灌 胃 试 验 并 具 有 明 显 降 血 糖 效 果 （ 血 糖 值 由 25。7±1。6mmol/L 降低至 10。3±2。1mmol/L），麦胚降血糖肽能够显著降低高血糖小鼠血糖，但对血糖正常小 鼠并无影响。

毕业论文关键词：麦胚；降血糖肽；光谱分析；分离纯化；动物实验。

Abstract Wheat is one of the most important food crops in China, and wheat germ is the core of wheat kernel。 It is rich in high quality protein。 At present, the utilization efficiency of wheat germ protein in our country is relatively low。  Wheat germ  protein can generate amino acid sequence with hypoglycemic activity by enzymatic hydrolysis, which is also called hypoglycemic peptide。 In this paper, we study the changes of the secondary structure of wheat germ protein during ultrasonic pretreatment and enzymatic hydrolysis by spectroscopy study。 Wheat germ hypoglycemic peptide are prepared by ultrasonic assisted enzymatic, then the wheat germ hypoglycemic peptide are separated and purified by ultrafiltration, ion exchange chromatography and sephadex gel chromatography。 The structure of purified peptide is identified by liquid chromatography-mass spectrometry/ mass spectrometry (LC-MS/MS)。

To explore the protein secondary structure changes during the process of ultrasonic pretreatment and enzymatic hydrolysis, we use Fluorescence  spectroscopy, near-infrared Raman spectroscopy and Fourier transform infrared spectrum analysis of protein structure。 In the process of ultrasonic pretreatment, ultrasonic wave makes the secondary structure of the protein change to the fixed tendency, and the most obvious change is achieved at the optimum ultrasonic time。 In the process of enzymatic hydrolysis, because the protein molecules are constantly hydrolyzed by trypsin, the protein secondary structure is also changing, so the change of the law is not as obvious as the ultrasonic process。

The wheat germ protein are purified by ultrasonic assisted enzymatic hydrolysis,

and then purified by filtration system, 732 cation exchange resin and sephadex gel chromatography。 The first peak of Sephadex-G15 (C-II-2。1) isolated from wheat germ hypoglycemic peptides has the highest inhibition rate of α-glycosidase enzyme。 After LC-MS analysis, the sequence of the wheat germ hypoglycemic peptide which has the highest  α-glycosidase  inhibitory  activity  and  content  in  C-II-2。1  is  as  follows: m/z