4RGZ:
reference: Structure of recombinant prolidase from Thermococcus sibiricus in space group P21221., Timofeev V, Slutskaya E, Gorbacheva M, Boyko K, Rakitina T, Korzhenevskiy D, Lipkin A, Popov V, Acta Crystallogr F Struct Biol Commun. 2015 Aug 1;71(Pt 8):951-7. doi:, 10.1107/S2053230X15009498. Epub 2015 Jul 28. PMID: 26249680

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