2 5-aminolevulinate <=> porphobilinogen + 2 H2O + H(+)
2 5-aminolevulinate <=> porphobilinogen + 2 h2o + h(+)
2 5-aminolevulinate <=> porphobilinogen + 2 H2O + H(+)
2 5-aminolevulinate <=> porphobilinogen + 2 h2o + h(+)