4-Hydroxycinnamate decarboxylase

4-Hydroxycinnamate decarboxylase is an enzyme that uses "p"-coumaric acid to produce 4-ethylphenol.
"p"-Coumaric acid is the precursor of 4-ethylphenol produced by the yeast "Saccharomyces" and "Brettanomyces" in wine. The yeast converts this to 4-vinylphenol via the enzyme cinnamate decarboxylase.
4-Hydroxycinnamate decarboxylase can also be induced in bacteria species such as "Klebsiella oxytoca" and works also with p-coumaric acid analogs such as caffeic acid, ferulic acid and E-2,4-dihydroxycinnamic acid.