It is a pleasure to acknowledge Prof. S. G. Sligar and Prof. Y. Lu of University of Illinois at Urbana–Champaign, for the kind gift of the sperm whale Mb gene. This work was supported by the National Natural Science Foundation of China (31370812, 21807058, and 31200642), Special Scientific Research Funds for Central Nonprofit Institutes, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences (20603022016011), and Financial Fund of the ministry of Agriculture and Rural Affairs, P. R. of China (NFZX2018).