Chen Hao, Ji Hongwu, Pan Chuang, Zhang Di, Su Weiming, Liu Shucheng, Deng Yijia, Huang Xiaodan
Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, China.
Hunan Provincial Key Laboratory of Soybean Products Processing and Safety Control, College of Food and Chemical Engineering, Shaoyang University, Shaoyang 422000, China.
Foods. 2021 Dec 23;11(1):35. doi: 10.3390/foods11010035.
Pigment proteins play a vital role in the red colour change of the red swamp crayfish () shell after cooking. In this study, two red-change-related pigment proteins with molecular weights of approximately 170 and 43 kDa-denoted as F1 and F2, respectively-were purified by ammonium sulphate salting-out and size exclusion chromatography. F1 and F2 entirely comprised homomultimeric protein complexes composed of 21 kDa subunits. LC-MS/MS analysis showed that the 21 kDa protein subunit belonged to the crustacyanin family, named . crustacyanin A2 (PcCRA2). The full-length cDNA of PcCRA2 was cloned, which encoded 190 amino acid residues and was highly homologous (91.58%) with crustacyanin A. The predicted 3D structure showed that PcCRA2 had a β-barrel structure for pigment encapsulation. The colour change of F1 was first detected at 40 °C, and the red change occurred upon heating above 60 °C. Additionally, with increasing temperature, its β-sheet content increased, and its α-helix content reduced. Correlation analysis showed that the redness value of F1 was significantly related to the heating temperature and the β-sheet content.
色素蛋白在克氏原螯虾烹饪后外壳的红色变化中起着至关重要的作用。在本研究中，通过硫酸铵盐析和尺寸排阻色谱法纯化了两种与红色变化相关的色素蛋白，其分子量分别约为170 kDa和43 kDa，分别表示为F1和F2。F1和F2完全由由21 kDa亚基组成的同多聚体蛋白复合物组成。LC-MS/MS分析表明，21 kDa蛋白亚基属于虾青素结合蛋白家族，命名为克氏原螯虾虾青素结合蛋白A2（PcCRA2）。克隆了PcCRA2的全长cDNA，其编码190个氨基酸残基，与克氏原螯虾虾青素结合蛋白A高度同源（91.58%）。预测的三维结构表明，PcCRA2具有用于色素包封的β-桶状结构。F1的颜色变化在40℃时首次检测到，在60℃以上加热时发生红色变化。此外，随着温度升高，其β-折叠含量增加，α-螺旋含量降低。相关性分析表明，F1的红色值与加热温度和β-折叠含量显著相关。
