Enzymic formation of p-hydroxybenzoate from p-hydroxycinnamate

An enzyme that converts p-hydroxycinnamate into p-hydroxybenzoate was found in rat liver. It is localized in the mitochondria and requires ATP. The activity is lost when the mitochondria are stored frozen overnight. Addition of magnesium chloride, cytochrome c, GSH, coenzyme A or potassium cyanide did not have any effect on the activity. When the rats were fed with alpha-p-chlorophenoxyisobutyrate, the rate of formation of p-hydroxybenzoate increased twofold. The reaction has some similar properties to fatty acid oxidation, but appears to be different in many respects.