PROSITE documentation PDOC00461Porphobilinogen deaminase cofactor-binding site
Porphobilinogen deaminase (EC 2.5.1.61), or hydroxymethylbilane synthase, is an enzyme involved in the biosynthesis of porphyrins and related macrocycles. It catalyzes the assembly of four porphobilinogen (PBG) units in a head to tail fashion to form hydroxymethylbilane.
The enzyme covalently binds a dipyrromethane cofactor to which the PBG subunits are added in a stepwise fashion. In the Escherichia coli enzyme (gene hemC), this cofactor has been shown [1] to be bound by the sulfur atom of a cysteine. The region around this cysteine is conserved in porphobilinogen deaminases from various prokaryotic and eukaryotic sources.
Last update:December 2004 / Pattern and text revised.
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| 1 | Authors | Miller A.D. Hart G.J. Packman L.C. Battersby A.R. |
| Title | Evidence that the pyrromethane cofactor of hydroxymethylbilane synthase (porphobilinogen deaminase) is bound to the protein through the sulphur atom of cysteine-242. | |
| Source | Biochem. J. 254:915-918(1988). | |
| PubMed ID | 3196304 |
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