4Y5F:
reference: X-ray radiation induces deprotonation of the bilin chromophore in crystalline D. radiodurans phytochrome., Li F, Burgie ES, Yu T, Heroux A, Schatz GC, Vierstra RD, Orville AM, J Am Chem Soc. 2015 Mar 4;137(8):2792-5. doi: 10.1021/ja510923m. Epub 2015 Feb, 18. PMID: 25650486

This OCA Structure page
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