核桃多肽的抗氧化活性及其分子量、氨基酸组成特性研究

目的:为了提高核桃粕利用价值,阐明核桃多肽抗氧化活性及其构效关系。方法:采用DA 201-C大孔树脂和Sephadex G-15葡聚糖凝胶分离纯化核桃粕蛋白酶解液,分析比较不同疏水性和不同分子量核桃多肽抗氧化活性及氨基酸组成特性。结果:经DA 201-C大孔树脂分离的多肽组分Ⅰ、Ⅱ、Ⅲ的抗氧化活性随洗脱溶剂疏水性增大而增大。组分Ⅲ经Sephadex G-15分离纯化得到a、b、c、d四个不同分子量多肽组分。分子量分布在400~700 Da的组分c具有最高的羟自由基清除能力,并含有较高的谷氨酸、天冬氨酸、亮氨酸、苯丙氨酸,与组分Ⅲ在氨基酸组成上具有相似性。结论:具有较好抗氧化活性的核桃多肽分子量小于800 Da,并具有疏水性较强,谷氨酸、天冬氨酸、亮氨酸、苯丙氨酸组成含量相对较高的结构特性。

Study on Antioxidant Activity of Walnut Polypeptide and Its Molecular Weight,Amino Acid Composition Characteristic

Objective:In order to improve the utilization value of walnut dregs and elucidate the antioxidant activity of walnut peptides and its structure-activity relationship. Methods:DA 201-C macroporous resin and Sephadex G-15 glucan gel were used to isolate and purify the enzymatic hydrolysis of walnut dregs protein by complex protease. The antioxidant activity and amino acid composition of walnut peptides with different hydrophobicities and molecular weights were analyzed and composed. Results:The antioxidant activities of polypeptide fractions I,II and III,which were separated by DA 201-C macroporous resin,increased with the increasing of the eluent hydrophobicity. Four different molecular weight polypeptide components of a,b,c,d were isolated and purified from component III by Sephadex G-15. Component c,which was similar to component III in amino acid composition,had the highest hydroxyl radical scavenging capacity and contained higher glutamate,aspartate,leucine and phenylalanine. Its molecular weight was distributed in 400~700 Da. Conclusion:Walnut polypeptide with better antioxidant activity had a molecular weight of less than 800 Da,it had the characteristics of strong hydrophobicity and relatively high composition contents of glutamic acid,aspartic acid,leucine and phenylalanine.