Nomilin Acetyl-Lyase, a Bacterial Enzyme for Nomilin Debittering of Citrus Juices

Nomilin acetyl-lyase, an enzyme responsible for the conversion of bitter nomilin to nonbitter obacunone was purified from cell-free extracts of Corynebacterium fuscians by (NH₄)₂SO₄ precipitation, followed by HPLC gel filtration and ion exchange chromatography. The electrophoretically pure preparation represented a 1050-fold increase in specific activity with a recovery of 38%. The enzyme, (MW 90,000) required sulfhydryl groups for its catalysis, had a pH optimum of 8.5, a K_m of 38.1 PM, and a V_max of 4.83 μmoles/min. Obacunone A-ring lactone hydrolase, which catalyzes the conversion of obacunone to obacunoate, was also purified from the extract by HPLC gel filtration.