Chemicals and Drugs

Hydroxymethylbilane Synthase

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 4.3.1.8

National Library of MedicineMedical Subject Headings2026

Structured Summary

Abstract

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 4.3.1.8

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Synonyms

15 entry terms
  • Hydroxymethylbilane Synthetase
  • Porphobilinogen Ammonia-Lyase
  • Porphobilinogen Deaminase
  • Pre-uroporphyrinogen Synthetase
  • Preuroporphyrinogen Synthetase
  • Uroporphyrinogen I Synthase
  • Ammonia-Lyase, Porphobilinogen
  • Deaminase, Porphobilinogen
  • Porphobilinogen Ammonia Lyase
  • Pre uroporphyrinogen Synthetase
  • Synthase, Hydroxymethylbilane
  • Synthase, Uroporphyrinogen I
  • Synthetase, Hydroxymethylbilane
  • Synthetase, Pre-uroporphyrinogen
  • Synthetase, Preuroporphyrinogen

MeSH Record

Aspects Covered

28 allowable subheadings

Indexed with the subheadings administration & dosage, adverse effects, analysis, antagonists & inhibitors, biosynthesis, blood, cerebrospinal fluid, chemical synthesis, chemistry, classification, drug effects, economics, genetics, history, immunology, isolation & purification, metabolism, pharmacokinetics, pharmacology, physiology, poisoning, radiation effects, standards, supply & distribution, therapeutic use, toxicity, ultrastructure, urine.

MeSH Record

History Note

98(75)

MeSH Record

Previous Indexing

  • Ammonia-Lyases (1973-1974)
  • Porphobilinogen (1973-1974)

MeSH Hierarchy

Tree Number

  1. D08.811w.913w.225.575

AMA Style

References

  1. National Library of Medicine. Hydroxymethylbilane Synthase. Medical Subject Headings (MeSH). 2026. Unique ID D011163. http://id.nlm.nih.gov/mesh/2026/D011163
  2. Hydroxymethylbilane Synthase. In: Wikidata. https://www.wikidata.org/wiki/Q24725195