6UJ6:
reference: X-ray structure of chromium(III)-containing transferrin: First structure of a physiological Cr(III)-binding protein., Petersen CM, Edwards KC, Gilbert NC, Vincent JB, Thompson MK, J Inorg Biochem. 2020 Sep;210:111101. doi: 10.1016/j.jinorgbio.2020.111101. Epub , 2020 May 23. PMID: 32650146

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).