3-Maleylpyruvic acid, or 3-maleylpyruvate, is a dicarboxylic acid formed by the oxidative ring opening of gentisic acid by gentisate 1,2-dioxygenase during the metabolism of tyrosine. It is converted into 3-fumarylpyruvate by maleylpyruvate isomerase.
In some organisms, the amino acid tyrosine is metabolised to gentisic acid. In the presence of the enzyme gentisate 1,2-dioxygenase and oxygen, this compound undergoes a ring-opening reaction to give 3-maleylpyruvic acid:
This reaction has been used to detect gentisic acid with a whole-cell biosensor developed from a 3-maleylpyruvic acid-inducible gene expression system and the gentisate 1,2-dioxygenase gene from chemolithoautotrophic bacterium Cupriavidus necator.
The enzyme maleylpyruvate isomerase converts 3-maleylpyruvic acid to its geometric isomer, 3-fumarylpyruvic acid.