Transferases;
Transferring alkyl or aryl groups, other than methyl groups;
Transferring alkyl or aryl groups, other than methyl groups (only sub-subclass identified to date)
BRITE hierarchy

porphobilinogen:(4-[2-carboxyethyl]-3-[carboxymethyl]pyrrol-2-yl)methyltransferase (hydrolysing)

4 porphobilinogen + H2O = hydroxymethylbilane + 4 NH3 [RN:R00084]

R00084
Reaction

porphobilinogen [CPD:C00931];
H2O [CPD:C00001]

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.

EC 2.5.1.61 created 1972 as EC 4.3.1.8, transferred 2003 to EC 2.6.1.61