PROSITE documentation PDOC00461Porphobilinogen deaminase cofactor-binding site
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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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