National Laboratory of Biomacromolecules;
CAS Center for Excellence in Biomacromolecules;
Institute of Biophysics;
Chinese Academy of Sciences;
Beijing 100101;
China;
The Institute of Medicinal Plant Development;
Chinese Academy of Medical Sciences(CAMS)and Peking Union Medical College(PUMC);
Beijing 100193;
China;
University of Chinese Academy of Sciences;
Beijing 100049;
China;
alpha-2-macroglobulin; Cryo-EM; dynamic transformation; protease inhibitor; structure;