食品科学

• 基础研究 • 上一篇    下一篇

紫薯花色苷-蛋白复合物的制备及结构表征

郭 莹,江 甜,李书艺,祝振洲,何静仁*   

  1. 武汉轻工大学食品科学与工程学院,湖北 武汉 430023
  • 出版日期:2016-11-15 发布日期:2016-11-18

Preparation and Structure Identification of Anthocyanins-Protein Complexes from Purple Sweet Potato

GUO Ying, JIANG Tian, LI Shuyi, ZHU Zhenzhou, HE Jingren*   

  1. College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China
  • Online:2016-11-15 Published:2016-11-18

摘要:

采用硫酸铵沉淀法制备紫薯花色苷-蛋白复合物,经二乙氨基乙基纤维素52和Sephadex G-75葡聚糖凝胶纯化得紫薯纯蛋白,利用聚丙烯酰胺凝胶电泳测定紫薯蛋白及紫薯花色苷-蛋白复合物的分子质量,运用紫外、荧光、红外和圆二色谱多种光谱方法对紫薯蛋白及紫薯花色苷-蛋白复合物进行结构表征。结果表明:紫薯蛋白及花色苷-蛋白复合物的分子质量无明显差异,均存在4 种不同的分子质量分布:58、24、18 kD和14 kD。紫薯蛋白紫外最大吸收峰位于200 nm波长处,复合物的紫外光谱略有红移且吸收增强。紫薯蛋白荧光光谱的最大发射波长是340 nm,而复合物的荧光强度几乎完全猝灭。紫薯蛋白的红外光谱图具有酰胺带特征吸收,复合物的红外光谱峰形和吸收强度发生明显变化。圆二色谱图显示紫薯蛋白二级结构以β-折叠(43.6%)和无规卷曲(45.7%)为主,β-转角(10.6%)次之,而复合物以β-折叠(72.2%)为主,无规卷曲(27.8%)含量降低,β-转角消失。

关键词: 紫薯, 花色苷-蛋白复合物, 紫薯蛋白, 结构表征

Abstract:

Purple sweet potato anthocyanins-protein complexes were extracted with hot water and precipitated by adding
ammonium sulfate to 60% saturation. Purple sweet potato protein (PSPP) was further purified from the complexes by DEAE-52
ion exchange chromatography and Sephadex G-75 gel filtration chromatography. The molecular weights of PSPP and the
complexes were determined by SDS-PAGE. A series of spectroscopic methods were used to characterize their structures.
Results showed that there was no difference between PSPP and its complexes with anthocyanins in molecular weight.
SDS-PAGE analysis exhibited four bands with molecular weights of 58, 24, 18 and 14 kD, respectively. The UV absorption
spectra of both PSPP and the complexes showed a peak at 200 nm, but additional peaks and red-shift phenomenon of the
complexes were observed when compared to PSPP. The maximum fluorescence emission wavelength of PSPP was 340 nm,
and the intensity for the complexes was almost entirely quenched. FTIR spectra of PSPP had characteristic amide bands, and
the shape and intensity of the complexes revealed a significant change. Circular dichroism (CD) revealed that PSPP had a
secondary structure characterized by β-sheets (43.6%) and random coils (45.7%), β-turns (10.6%), while the complexes had
higher content of β-sheets (72.2%) and decreased content of random coils (27.8%), and showed the disappearance of β-turns.

Key words: purple sweet potato, anthocyanins-protein complexes, purple sweet potato protein, structure characterization

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