| Synonyms |
(HMB)-synthase, AN0121.3, EC 4.3.1.8, HemC, hepatic porphobilinogen deaminase, HMB synthase, HMB-S, HMBS, HMBS1a-synthase, HMBS1b-synthase, HMBS2a-synthase, HMBS2b-synthase, human non-erythropoietic PBGD isoform, human PBGD, human porphobilinogen deaminase, hydroxymethylbilane synthase, More, PBG deaminase, PBG-D, PBG-deaminase, PBGD, PGB-D, porphobilinogen ammonia-lyase (polymerizing), porphobilinogen deaminase, pre-uroporphyrinogen synthase, preuroporphyrinogen synthase, preuroporphyrinogen synthetase, synthase, uroporphyrinogen I, uPBGD, UPGI-S, URO-S, urogenI synthase, uroporphyrinogen I synthase, uroporphyrinogen I synthetase, uroporphyrinogen synthase, uroporphyrinogen synthetase |
| Comments |
The enzyme works by stepwise addition of pyrrolylmethyl groups until a hexapyrrole is present at the active centre. The terminal tetrapyrrole is then hydrolysed to yield the product, leaving a cysteine-bound dipyrrole on which assembly continues. In the presence of a second enzyme, EC 4.2.1.75 (uroporphyrinogen-III synthase), which is often called cosynthase, the product is cyclized to form uroporphyrinogen-III. If EC 4.2.1.75 is absent, the hydroxymethylbilane cyclizes spontaneously to form uroporphyrinogen I. |
