白木通籽分离蛋白的理化与功能性质研究

Physicochemical and functional properties of protein isolate extracted from Akebia trifoliata var. australis seed

以白木通籽为原料,采用碱提酸沉法,制备白木通籽分离蛋白(API),并对其理化性质与功能性质进行了分析。结果表明:白木通籽分离蛋白含17种氨基酸,其中谷氨酸和天门冬氨酸的含量相对较高,有贮藏蛋白的共性。苏氨酸为白木通籽分离蛋白的第一限制性氨基酸。通过SDS-PAGE分析,白木通籽分离蛋白的亚基分子量范围为25～35ku。圆二色性光谱分析表明,白木通籽分离蛋白的二级结构主要由β-折叠和无规则卷曲组成,含量分别为31.2%和36.6%。白木通籽分离蛋白的等电点在pH4～5之间,在此pH范围内,蛋白的溶解性和起泡能力均最低。

Akebia trifoliata var. australis seed protein isolate （API）was prepared using the methods of alkali extraction and acid precipitation.The physicochemical and functional properties of API were characterized.The results showed that API contained 17 kinds of amino acids. Glutamic acid and aspartic acid were the most abundant amino acids in API ,consistent with most storage proteins.With respect to nutritional parameter,threonine was found as the first limiting amino acids for API.From the analysis of SDS-PAGE, molecular weights of API were from 25.0-35.0ku. Accounting for 31.2% and 36.6%. 13-strand and random coil were found to be the major secondary structures in API.The isoelectric point of API was between 4 and 5. Protein solubility and the foaming capacity were minimal at that pH values.