Characterization of a Novel Lutein Cleavage Dioxygenase, EhLCD, from Enterobacter hormaechei YT-3 for the Enzymatic Synthesis of 3-Hydroxy-β-ionone from Lutein

3-Hydroxy-β-ionone, a flavor and fragrance compound with fruity violet-like characteristics, is widely applied in foodstuff beverages, currently produced using synthetic chemistry. In this study, novel lutein cleavage enzyme (EhLCD) was purified characterized from Enterobacter hormaechei YT-3 to convert 3-hydroxy-β-ionone. Enzyme EhLCD homogeneity by ammonium sulfate precipitation, Q-Sepharose, phenyl-Sepharose, Superdex 200 chromatography. The molecular mass of EhLCD, obtained SDS-PAGE, approximately 50 kDa. exhibited the highest activity toward lutein, followed zeaxanthin, β-cryptoxanthin, β-carotene, suggesting that higher catalytic efficiency for carotenoid substrates bearing 3-hydroxy-ionone rings. Isotope-labeling experiments showed incorporated oxygen O2 into 3-hydroxy-β-ionone dioxygenase reaction mechanism different substrates. These results indicated first bacterial dioxygenase. Active also confirmed be Fe2+-dependent protein 1 molar equivalent non-haem Fe2+. displayed optimal at 45 °C pH 8.0. optimum concentrations substrate, enzyme, Tween 40 production were 60 μM lutein/L, 1.5 U/mL, 2% (w/v), respectively. Under conditions, (637.2 mg/L) min conversion 87.0% (w/w), indicating potential candidate enzymatic synthesis biotechnological applications.