2G3F:
reference: A catalytic mechanism revealed by the crystal structures of the imidazolonepropionase from Bacillus subtilis., Yu Y, Liang YH, Brostromer E, Quan JM, Panjikar S, Dong YH, Su XD, J Biol Chem. 2006 Dec 1;281(48):36929-36. Epub 2006 Sep 21. PMID: 16990261

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