Enzymatic reduction of levulinic acid by engineering the substrate specificity of 3-hydroxybutyrate dehydrogenase

► A novel activity toward levulinic acid was generated by engineering of 3HBDH. ► Levulinic acid was converted to 4-hydroxyvaleric acid by the engineered 3HBDH. ► Engineering strategy was proposed and validated by molecular docking simulation. ► Approximately 60% conversion of levulinic acid was achieved by the engineered enzyme.