2XDF:
reference: Solution Structure of the 128 kDa Enzyme I Dimer from Escherichia coli and Its 146 kDa Complex with HPr Using Residual Dipolar Couplings and Small- and Wide-Angle X-ray Scattering., Schwieters CD, Suh JY, Grishaev A, Ghirlando R, Takayama Y, Clore GM, J Am Chem Soc. 2010 Aug 23. PMID: 20731394

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