Barends Thomas R M, Dunn Michael F, Schlichting Ilme
Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, D-69120 Heidelberg, Germany.
Curr Opin Chem Biol. 2008 Oct;12(5):593-600. doi: 10.1016/j.cbpa.2008.07.011.
Tryptophan synthase (TrpS) is a pyridoxal phosphate-containing bifunctional enzyme that catalyzes the last two steps in the biosynthesis of L-tryptophan. Indole, an intermediate generated at the active site of the alpha-subunit is channeled via a 25 A long tunnel to the beta-active site where it reacts with an aminoacrylate intermediate derived from L-serine. The two reactions are kept in phase by allosteric interactions between the two subunits. The recent development of novel alpha-site ligands and alpha-reaction transition state analogs combined with kinetic and crystal structure analysis of Salmonella typhimurium tryptophan synthase has provided new insights into the allosteric regulation of substrate channeling, the reaction mechanisms of the alpha and beta active sites, and the influence of structural dynamics.
色氨酸合酶（TrpS）是一种含磷酸吡哆醛的双功能酶，催化L-色氨酸生物合成的最后两步。吲哚是在α亚基活性位点产生的中间体，通过一条25埃长的通道输送到β活性位点，在那里它与源自L-丝氨酸的氨基丙烯酸酯中间体反应。这两个反应通过两个亚基之间的变构相互作用保持同步。新型α位点配体和α反应过渡态类似物的最新进展，结合鼠伤寒沙门氏菌色氨酸合酶的动力学和晶体结构分析，为底物通道的变构调节、α和β活性位点的反应机制以及结构动力学的影响提供了新的见解。
