3E08:
reference: Histidine 55 of tryptophan 2,3-dioxygenase is not an active site base but regulates catalysis by controlling substrate binding., Thackray SJ, Bruckmann C, Anderson JL, Campbell LP, Xiao R, Zhao L, Mowat CG, Forouhar F, Tong L, Chapman SK, Biochemistry. 2008 Oct 7;47(40):10677-84. Epub 2008 Sep 11. PMID: 18783250

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