Ammonia-Lyase, Porphobilinogen

An enzyme that catalyzes the tetrapolymerization of the monopyrrole PORPHOBILINOGEN into the hydroxymethylbilane preuroporphyrinogen (Uroporphyrinogens) in several discrete steps. It is the third enzyme in the 8-enzyme Biosynthetic Pathway of Heme. In Humans, deficiency in this enzyme encoded by HMBS (or PBGD) Gene results in a form of neurological Porphyria (Porphyria, Acute Intermittent). This enzyme was formerly listed as EC