Chemical and Biochemical Properties of 2-Hydroxypentadienoic Acid, a Homologue of Enolpyruvic Acid.

2-Hydroxypentadienoic acid is shown to be a biochemical intermediate on the phenylpropionate catabolic pathway of Escherichia coli; its stability and ketonisation behaviour are compared with those of its homologue, enolpyruvate.