4X4K:
reference: Incorporation of copper ions into crystals of T2 copper-depleted laccase from Botrytis aclada., Osipov EM, Polyakov KM, Tikhonova TV, Kittl R, Dorovatovskii PV, Shleev SV, Popov VO, Ludwig R, Acta Crystallogr F Struct Biol Commun. 2015 Dec 1;71(Pt 12):1465-9. doi:, 10.1107/S2053230X1502052X. Epub 2015 Nov 18. PMID: 26625287

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