5K9Y:
reference: The role of local residue environmental changes in thermostable mutants of the GH11 xylanase from Bacillus subtilis., Silva SB, Pinheiro MP, Fuzo CA, Silva SR, Ferreira TL, Lourenzoni MR, Nonato MC, Vieira DS, Ward RJ, Int J Biol Macromol. 2017 Apr;97:574-584. doi: 10.1016/j.ijbiomac.2017.01.054., Epub 2017 Jan 18. PMID: 28109807

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