Purification and Characterisation of Two Novel Pigment Proteins from the Carapace of Red Swamp Crayfish (<i>Procambarus clarkii</i>)
Hao Chen,
Hongwu Ji,
Chuang Pan,
Di Zhang,
Weiming Su,
Shucheng Liu,
Yijia Deng,
Xiaodan Huang
Affiliations
Hao Chen
Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, China
Hongwu Ji
Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, China
Chuang Pan
Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian 116034, China
Di Zhang
Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, China
Weiming Su
Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, China
Shucheng Liu
Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, China
Yijia Deng
Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, China
Xiaodan Huang
Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, China
Pigment proteins play a vital role in the red colour change of the red swamp crayfish (Procambarus clarkii) 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 P. clarkii crustacyanin A2 (PcCRA2). The full-length cDNA of PcCRA2 was cloned, which encoded 190 amino acid residues and was highly homologous (91.58%) with Cherax quadricarinatus 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.
