5KWF:
reference: An extended N-H bond, driven by a conserved second-order interaction, orients the flavin N5 orbital in cholesterol oxidase., Golden E, Yu LJ, Meilleur F, Blakeley MP, Duff AP, Karton A, Vrielink A, Sci Rep. 2017 Jan 18;7:40517. doi: 10.1038/srep40517. PMID: 28098177

This OCA Structure page
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