초록
<P><B>ABSTRACT</B></P><P>Sugar phosphates cannot be produced easily by microbial fermentation because negatively‐charged compounds cannot be secreted across intact cell membrane. D‐xylulose 5‐phosphate (Xu5P), a very expensive sugar phosphate, was synthesized from D‐xylose and polyphosphate catalyzed by enzyme cascades in one pot. The synthetic enzymatic pathway comprised of xylose isomerase and xylulokinase was designed to produce Xu5P, along with a third enzyme, polyphosphate kinase, responsible for in site ATP regeneration. Due to the promiscuous activity of the ATP‐based xylulokinase from a hyperthermophilic bacterium <I>Thermotoga maritima</I> on polyphosphate, the number of enzymes in the pathway was minimized to two without polyphosphate kinase. The reactions catalyzed by the two‐enzyme and three‐enzyme pathways were compared for Xu5P production, and the reaction conditions were optimized by examining effects of reaction temperature, enzyme ratio and substrate concentration. The optimized two‐enzyme system produced 32 mM Xu5P from 50 mM xylose and polyphosphate after 36 h at 45°C. Biosynthesis of less costly Xu5P from D‐xylose and polyphosphate could be highly feasible via this minimized two‐enzyme pathway. Biotechnol. Bioeng. 2016;113: 275–282. © 2015 Wiley Periodicals, Inc.</P>