2CLL:
reference: Allosteric regulation of substrate channeling in tryptophan synthase: modulation of the L-serine reaction in stage I of the beta-reaction by alpha-site ligands., Ngo H, Kimmich N, Harris R, Niks D, Blumenstein L, Kulik V, Barends TR, Schlichting I, Dunn MF, Biochemistry. 2007 Jul 3;46(26):7740-53. Epub 2007 Jun 9. PMID: 17559232

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