The enzyme works equally well with 4-hydroxybenzoate but shows low activity towards benzoate, 4-aminobenzoate, 3-aminobenzoate, 3-fluorobenzoate, 4-fluorobenzoate, 3-chlorobenzoate, and 4-chlorobenzoate. There is no activity with 3,4-dihydroxybenzoate, 2,3-dihydroxybenzoate, and 2-hydroxybenzoate as substrates.