Involved in the degradation of gentisate (PubMed:7400101, PubMed:23204427). Catalyzes the hydrolysis of 3-maleylpyruvate, the ring-cleavage product of gentisate (PubMed:7400101, PubMed:23204427). 3-maleylpyruvate + H2O = H(+) + maleate + pyruvate Activated by Mn(2+) (PubMed:7400101, PubMed:23204427). Inhibited by Ni(2+), Cd(2+), Co(2+) or Cu(2+) (PubMed:23204427). Optimum pH is 7.2-7.7 (PubMed:7400101). Optimum pH is 7.6 (PubMed:23204427). Optimum temperature is 30 degrees Celsius. Homodimer. Induced by 3-hydroxybenzoate. Disruption mutant can still grow on gentisate. Belongs to the FAH family.