3VSR:
reference: Crystal structure of a lactosucrose-producing enzyme, Arthrobacter sp. K-1 beta-fructofuranosidase., Tonozuka T, Tamaki A, Yokoi G, Miyazaki T, Ichikawa M, Nishikawa A, Ohta Y, Hidaka Y, Katayama K, Hatada Y, Ito T, Fujita K, Enzyme Microb Technol. 2012 Dec 10;51(6-7):359-65. doi:, 10.1016/j.enzmictec.2012.08.004. Epub 2012 Aug 16. PMID: 23040392

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