An aldo-keto reductase with 2-keto- L-gulonate reductase activity functions in L-tartaric acid biosynthesis from vitamin C in Vitis vinifera

Unravelling the origin of wine’s sharp flavour

30 January 2020

A key step by which grapevines produce tartaric acid, an important component for wine colour and flavour, has been discovered by a University of Adelaide-led team.

Tartaric acid is produced by grapevines, and it gives wine its pleasantly sharp flavour.

Previous research had shown that tartaric acid is produced by degradation of ascorbic acid (vitamin C) in grapevines. But not all the enzymes involved in the multistep conversion of ascorbic acid to tartaric acid in the plant had been identified.

Researchers have now identified the enzyme catalysing one step in the process, in which the ascorbate breakdown product 2-keto-L-gulonic acid is converted to L-idonic acid.

The team did this by searching for grapevine enzymes with a similar structure to a known enzyme from E. coli that catalyses a closely related reaction. The grapevine enzyme they identified was the first of its kind discovered in any plant.

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References

1. Journal of Biological Chemistry 294, 15932–15946 (2019). doi: 10.1074/jbc.RA119.010196