Catalyzes the glutathione dependent oxygenation of dichloroacetic acid to glyoxylic acid in vitro. Has no glutathione thioltransferase activity with 4-hydroxynonenal (4-HNE), adrenochrome, phenethyl isothiocyanate (PEITC), 5-hydroperoxyeicosatetraenoic acid ((5S)-HpETE), prostaglandin A2 (PGA2) or 2-hydroxyethyldisulfide (HED). 4-maleylacetoacetate = 4-fumarylacetoacetate glutathione + RX = a halide anion + an S-substituted glutathione + H(+) Glutathione is required for the MAAI activity. Amino-acid degradation; L-phenylalanine degradation; acetoacetate and fumarate from L-phenylalanine: step 5/6. Expressed during embryogenesis. Belongs to the GST superfamily. Zeta family. Extended N-terminus. Extended N-terminus.