{PDOC00461}
{PS00533; PORPHOBILINOGEN_DEAM}
{BEGIN}
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* Porphobilinogen 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.

-Consensus pattern: E-[KR]-x-[LIVMFAT]-x(3)-[LIVMFAC]-x-[GSALV]-[GSANHD]-C-x-
                    [IVTACS]-[PLA]-[LIVMF]-[GSA]
                    [C is the cofactor attachment site]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: December 2004 / Pattern and text revised.

[ 1] Miller A.D., Hart G.J., Packman L.C., Battersby A.R.
     "Evidence that the pyrromethane cofactor of hydroxymethylbilane
     synthase (porphobilinogen deaminase) is bound to the protein through
     the sulphur atom of cysteine-242."
     Biochem. J. 254:915-918(1988).
     PubMed=3196304
{END}