School of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
Chembiochem. 2017 Feb 16;18(4):382-386. doi: 10.1002/cbic.201600471. Epub 2017 Jan 20.
β-Methyltryptophans (β-mTrp) are precursors in the biosynthesis of bioactive natural products and are used in the synthesis of peptidomimetic-based therapeutics. Currently β-mTrp is produced by inefficient multistep synthetic methods. Here we demonstrate how an engineered variant of tryptophan synthase from Salmonella (StTrpS) can catalyse the efficient condensation of l-threonine and various indoles to generate β-mTrp and derivatives in a single step. Although l-serine is the natural substrate for TrpS, targeted mutagenesis of the StTrpS active site provided a variant (βL166V) that can better accommodate l-Thr as a substrate. The condensation of l-Thr and indole proceeds with retention of configuration at both α- and β-positions to give (2S,3S)-β-mTrp. The integration of StTrpS (βL166V) with l-amino acid oxidase, halogenase enzymes and palladium chemocatalysts provides access to further d-configured and regioselectively halogenated or arylated β-mTrp derivatives.
β-甲基色氨酸（β-mTrp）是生物活性天然产物生物合成的前体，用于合成基于肽模拟物的治疗药物。目前，β-mTrp 的生产采用效率低下的多步合成方法。在这里，我们展示了来自沙门氏菌的色氨酸合酶（StTrpS）的一种工程变体如何能够在一步中有效地催化 l-苏氨酸和各种吲哚的缩合，生成 β-mTrp 和衍生物。尽管 l-丝氨酸是 TrpS 的天然底物，但 StTrpS 活性位点的靶向突变提供了一种变体（βL166V），可以更好地适应 l-Thr 作为底物。l-Thr 和吲哚的缩合在 α-和 β-位均保留构型，得到（2S，3S）-β-mTrp。StTrpS（βL166V）与 l-氨基酸氧化酶、卤化酶和钯化学催化剂的集成提供了进一步的 d-构型和区域选择性卤化或芳基化β-mTrp 衍生物的途径。
