One-Pot Bioconversion of l-Arabinose to l-Ribulose in an Enzymatic Cascade

• Main Authors: Litavadee Chuaboon, Thanyaporn Wongnate, Pangrum Punthong, Cholpisit Kiattisewee, Narin Lawan, Chia Yi Hsu, Chun Hung Lin, Uwe T. Bornscheuer, Pimchai Chaiyen
• Format: Journal
• Published: 2019
• Subjects: Chemical Engineering; Chemistry
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85060784297&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/63605
• Institution: Chiang Mai University

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim This work reports the one-pot enzymatic cascade that completely converts l-arabinose to l-ribulose using four reactions catalyzed by pyranose 2-oxidase (P2O), xylose reductase, formate dehydrogenase, and catalase. As wild-type P2O is specific for the oxidation of six-carbon sugars, a pool of P2O variants was generated based on rational design to change the specificity of the enzyme towards the oxidation of l-arabinose at the C2-position. The variant T169G was identified as the best candidate, and this had an approximately 40-fold higher rate constant for the flavin reduction (sugar oxidation) step, as compared to the wild-type enzyme. Computational calculations using quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) showed that this improvement is due to a decrease in the steric effects at the axial C4-OH of l-arabinose, which allows a reduction in the distance between the C2-H and flavin N5, facilitating hydride transfer and enabling flavin reduction.