Professor Toshiki Furuya from Tokyo University of Science (TUS) and his graduate students Shizuka Fujimaki and Satsuki Sakamoto have successfully developed an enzyme that generates vanillin from plant-derived ferulic acid using genetic engineering approaches.

Globally, vanilla extract is a widely used flavoring compound in food products and cosmetics. The pleasant and sweet smell of this classic flavor comes from the chemical compound vanillin found in the seed pods of vanilla plants belonging to the orchid family. Vanillin is synthesized by the conversion of ferulic acid by the enzyme VpVAN. Laboratory biosynthesis of vanillin from plant-derived VpVAN yields only very small quantities. While chemically derived vanilla essences are available, they do not match the flavor of natural vanilla extract, and the demand for the latter continues to remain high. Additionally, climatic restrictions for cultivating vanilla plants, and the relatively small yield obtained per plant, have led to a dwindling supply and a surge in the price of natural vanilla extract.

The TUS team used genetic engineering approaches to modify the molecular structure of Ado, an oxidase enzyme that adds an oxygen atom to the substrate isoeugenol. In its native state, Ado cannot convert ferulic acid into vanillin. Using structural modeling analysis, the researchers were able to predict amino acid changes in Ado which would enable its interaction with ferulic acid. They replaced phenylalanine and valine amino acid residues at specific positions in the structure of Ado with various other amino acids and examined the ferulic acid conversion ability of the various engineered mutant proteins.

They found a mutant protein that stably reacted with ferulic acid and exhibited high conversion activity. Notably, the engineered enzyme did not require any cofactors for conversion and produced vanillin on a gram scale per liter of reaction solution, with a higher catalytic efficiency and affinity than that of the wild-type enzyme. The reaction only required mixing of the ferulic acid and air at room temperature, making it a simple, sustainable, and economically scalable process.

For more details, read the news release from TUS Media Relations.

See https://www.isaaa.org/kc/cropbiotechupdate/article/default.asp?ID=20828