1. Two molecules of this intermediate become linked to form porphobilinogen . 2. Porphobilinogen deaminase is involved in the third step of the heme biosynthetic pathway.3. Porphobilinogen deaminase usually exists in dimer units in the cytoplasm of the cell.4. An inhibitor of porphobilinogen synthase with this mechanism of action has been documented. 5. The colorless porphobilinogen is changed to the dark colored porphobilin due to oxygen exposure. 6. Hereditary insufficiency of porphobilinogen synthase is called porphobilinogen synthase ( or ALA dehydratase ) deficiency poprhyria. 7. Hereditary insufficiency of porphobilinogen synthase is called porphobilinogen synthase ( or ALA dehydratase ) deficiency poprhyria. 8. The porphobilinogen synthase catalyzed reaction is the first common step in the biosynthesis of all biological tetrapyrroles. 9. PBG is then converted into hydroxymethyl bilane by the enzyme porphobilinogen deaminase, also known as hydroxymethylbilane synthase. 10. All natural tetrapyrroles, including hemes, chlorophylls and vitamin B 12, share porphobilinogen as a common precursor.
