Abstract：The structure characteristic of soybean selenoprotein and soy protein isolate (SPI) were investigated with fluorescence, ultraviolet and Fourier transform infrared (FTIR) spectrum. The unfolding process of two proteins was analyzed with fluorescence phase diagram method. The stability of emulsion properties and the influence of concentration, temperature and pH on the conformation of soy selenoproteins were also determined. The results indicated that the covalent disulfide bond of soybean selenoprotein molecules was damaged; the hydrogen bonding become weak; the hydrophobic interactions were enhanced and the protein chain molecules were extended. Soybean selenoprotein displayed only “folding” and “loose” state in solution, which illustrated soybean selenoprotein more tend to hydrolysis when compared with soybean protein. With temperature increasing, the fluorescence quenching effect occurred and the hydrophobicity of soy selenoproteins was also gradually increased, which reflected the protein molecules tends to be folded. In the range of pH 2.8～8.0, the Trp residue of soybean selenoprotein was mainly distributed in the polarity of the external environment and presented different conformational change on both sides of the isoelectric point under different pH value. In acidic environment, the soybean selenoprotein was easy to appear conformational transition from loose to fold. But it was conducive for soybean selenoprotein to existence in loose structure in alkaline conditions. In addition, the emulsifying properties of soybean selenoprotein were analyzed based on UV spectral data. Results showed that lower temperature helps to enhancement the emulsification but unfavorable the stability of the soybean selenoprotein.
[1] TIAN Jun-mei, ZHANG Ding, FU Rui-juan, et al(田俊梅, 张 丁, 付瑞娟, 等). Soybean Science(大豆科学), 2010, 29(3): 534. [2] Thavarajah D, Ruszkowski J, Vandenberg A. Journal of Agricultural and Food Chemistry, 2008, 56: 10747. [3] Finley J W. Journal of the Science of Food and Agriculture, 2007, 87(10): 1620. [4] LIU Hong, YANG Hui, AI Min-xian(刘 红, 阳 辉, 艾民仙). Acta Nutrimenta Sinica(营养学报), 2012, 34(3): 238. [5] Eckenro B, Harris K, Turanov A, et al. Biochemistry, 2006, 45：5158. [6] HUANG Yan-sheng, NING Zheng-xiang, WU Xiao-yong(黄延盛, 宁正祥, 吴小勇). Modern Food Science and Technology(现代食品科技), 2013, 29(6): 1273. [7] LIU Ying, PENG Chang-de, LAN Xiu-feng, et al(刘 莹、彭长德、兰秀风，等). Acta Physica Sinica(物理学报), 2005, 54(11): 5455. [8] Philip G R, Brian R G, DavidA F G, et al. Journal of Agricultural and Food Chemistry, 2007, 55: 516. [9] ZHANG Tan, BIAN Liu-jiao(张 潭, 边六交). Chemical Journal of Chinese Universities(高等学校化学学报)，2011, 32(7): 1497. [10] LONG Guo-hui, JI Yuan, PAN Hong-bin, et al(龙国徽, 纪 媛, 潘洪斌, 等). Journal of Jilin University(吉林大学学报), 2014, 52(4): 840. [11] PENG Gang, LIU Bai-ling, ZHAO Chun-xia, et al(彭 刚, 刘白玲, 赵春霞, 等). Journal of the Graduate School of the Chinese Academy of Sciences(中国科学院研究生院学报), 2011, 28(1): 12. [12] WANG Zhong-jiang, JIANG Lian-zhou, WEI Dong-xu, et al.(王中江, 江连州, 魏冬旭, 等). Food Science(食品科学)，2012, 33(11): 47.
