3PR2:
reference: X-ray and NMR crystallography in an enzyme active site: the indoline quinonoid intermediate in tryptophan synthase., Lai J, Niks D, Wang Y, Domratcheva T, Barends TR, Schwarz F, Olsen RA, Elliott DW, Fatmi MQ, Chang CE, Schlichting I, Dunn MF, Mueller LJ, J Am Chem Soc. 2011 Jan 12;133(1):4-7. Epub 2010 Dec 10. PMID: 21142052

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