3V17:
reference: The Fe(II) /alpha-ketoglutarate dependent taurine dioxygenases from Pseudomonas putida and Escherichia coli are tetramers., Knauer SH, Hartl-Spiegelhauer O, Schwarzinger S, Hanzelmann P, Dobbek H, FEBS J. 2012 Jan 5. doi: 10.1111/j.1742-4658.2012.08473.x. PMID: 22221834

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