4XZ9:
reference: Converting Transaldolase into Aldolase through Swapping of the Multifunctional Acid-Base Catalyst: Common and Divergent Catalytic Principles in F6P Aldolase and Transaldolase., Sautner V, Friedrich MM, Lehwess-Litzmann A, Tittmann K, Biochemistry. 2015 Jul 28;54(29):4475-86. doi: 10.1021/acs.biochem.5b00283. Epub , 2015 Jul 20. PMID: 26131847

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