Guo Jin, Higgins Melanie A, Daniel-Ivad Phillip, Ryan Katherine S
Department of Chemistry , University of British Columbia , Vancouver , British Columbia V6T 1Z4 , Canada.
J Am Chem Soc. 2019 Aug 7;141(31):12258-12267. doi: 10.1021/jacs.9b03307. Epub 2019 Jul 25.
Acyclic imines are unstable in aqueous conditions. For this reason, known imine reductases, which enable the synthesis of chiral amines, mainly intercept stable cyclic imines. Here we report the detailed biochemical and structural characterization of Bsp5, an imino acid reductase from the d-2-hydroxyacid dehydrogenase family that reduces acyclic imino acids produced by a partner oxidase. We determine a 1.6 Å resolution structure of Bsp5 in complex with d-arginine and coenzyme NADPH. Combined with mutagenesis work, our study reveals the minimal structural constraints for its biosynthetic activity. Furthermore, we demonstrate that Bsp5 can intercept more complex products from an alternate oxidase partner, suggesting that this oxidase-imino acid reductase pair could be evolved for biocatalytic conversion of l-amino acids to d-amino acids.
无环亚胺在水性条件下不稳定。因此，已知的能够合成手性胺的亚胺还原酶主要作用于稳定的环状亚胺。在此，我们报告了Bsp5的详细生化和结构特征，Bsp5是一种来自d-2-羟基酸脱氢酶家族的亚氨基酸还原酶，可还原由伴侣氧化酶产生的无环亚氨基酸。我们确定了Bsp5与d-精氨酸和辅酶NADPH复合物的分辨率为1.6 Å的结构。结合诱变工作，我们的研究揭示了其生物合成活性的最小结构限制。此外，我们证明Bsp5可以从另一种氧化酶伴侣中截获更复杂的产物，这表明这种氧化酶-亚氨基酸还原酶对可用于将l-氨基酸生物催化转化为d-氨基酸。
