Characterization of the p-Coumaric Acid Decarboxylase from Lactobacillus plantarum CECT 748T

It was previously reported that cell cultures from Lactobacillus plantarum CECT 748T were able to decarboxylate phenolic acids, such as p-coumaric, m-coumaric, caffeic, ferulic, gallic, and protocatechuic acid. The p-coumaric acid decarboxylase (PDC) from this strain has been overexpressed and purified. This PDC differs at its C-terminal end when compared to the previously reported PDC from L. plantarum LPCHL2. Because the C-terminal region of PDC is involved in enzymatic activity, especially in substrate activity, it was decided to biochemically characterize the PDC from L. plantarum CECT 748T. Contrarily to L. plantarum LPCHL2 PDC, the recombinant PDC from L. plantarum CECT 748T is a heat-labile enzyme, showing optimal activity at 22 °C. This PDC is able to decarboxylate exclusively the hydroxycinnamic acids p-coumaric, caffeic, and ferulic acids. Kinetic analysis showed that the enzyme has a 14-fold higher KM value for p-coumaric and caffeic acids than for ferulic acid. PDC catalyzes the formation of the corresponding 4-vinyl derivatives (vinylphenol and vinylguaiacol) from p-coumaric and ferulic acids, respectively, which are valuable food additives that have been approved as flavoring agents. The biochemical characteristics showed by L. plantarum PDC should be taken into account for its potential use in the food-processing industry.