Biosynthesis of Vanillin: Enzyme Involved in the Conversion of Ferulic Acid to Vanillin in Vanilla planifolia

The enzymes for shortening the phenylpropanoid side chain were partially purified by ion exchange and gel filtration column chromatographies after (NH 4 ) 2 SO 4 precipitation. The enzyme activities of each fraction were dependent on the presence of dithiothreitol (DTT). The optimum pH and the molecular weight of the enzyme in one fraction were approximately 7.0 and 17,000, respectively. The enzyme activity of ferulic acid toward 4-coumaric acid in the same fraction was about 16%. The enzyme activity was activated by the addition of 0.5 mM Fe 2+ . We propose that 2,3-dioxygenase catalyzes the reaction from ferulic acid to vanillin in Vanilla planifolia .