Efficient synthesis of an antiviral drug intermediate using overexpressed short‐chain dehydrogenase and cross‐linked enzyme aggregates stabilization

Abstract

AbstractBACKGROUND(2R,3S)‐N‐tert‐Butoxycarbonyl‐3‐amino‐1‐chloro‐2‐hydroxy‐4‐phenylbutane (1b) is key for the synthesis of the antiviral drug atazanavir. It can be obtained via the stereoselective bioreduction of (3S)‐3‐(N‐Boc‐amino)‐1‐chloro‐4‐phenyl‐butanone (1a) with short‐chain dehydrogenase/reductase (SDR) (EC 1.1.1.1). To develop a practical and cost‐effective biocatalytic approach with high stability and reusability, an SDR mutant (muSDR) from Novosphingobium aromaticivorans was overexpressed in Escherichia coli cell and immobilized by cross‐linked enzyme aggregates with enhanced stability and high efficiency.RESULTSmuSDR gene was successfully cloned and overexpressed in Escherichia coli and reduced 1a to 1b with high stereoselectivity. Four resin‐bound muSDR and cross‐linked muSDR aggregates (muSDR‐CLEAs) were prepared and compared. With addition of Tween‐80, the muSDR‐CLEAs demonstrated much higher activity recovery than resin‐bound muSDR. Compared with free enzyme, muSDR‐CLEAs demonstrated enhanced thermal, pH, and storage stabilities and could obtain 1b with high substrate concentration, high de, and complete conversion. The reusability of CLEAs was also determined as no significant activity loss was observed after seven batches of reactions. The space time yield of the bioreduction using muSDR‐CLEAs was 226.6 g∙L−1∙day−1.CONCLUSIONOverexpressed muSDR was efficiently immobilized, and it demonstrated superior stability and reusability. The recombinant muSDR and muSDR‐CLEAs are practical potential biocatalysts for industrial production of the atazanavir precursor. © 2020 Society of Chemical Industry (SCI)