succinyl-CoA + glycineBlack - reactantsH+protoporphyrinogen IXdelta-aminolevulinateRed - side productsFe2+rate limiting stepdelta-aminolevulinateFECHO2H2OALAS1PorphobilinogenH2OHMBSCPOXO2ALADhydroxymethylbilaneH2OH2O2ALAS2CoACO2UROSporphobilinogenPPOXNH3CO2URODuroporphyrinogen IIIcoproporphyrinogen IIIprotoporphyrin IXprotohemeCO2