CATH Classification

Domain Context

CATH Clusters

Superfamily Periplasmic binding protein-like II
Functional Family Porphobilinogen deaminase

Enzyme Information

2.5.1.61
Hydroxymethylbilane synthase.
based on mapping to UniProt P06983
4 porphobilinogen + H(2)O = hydroxymethylbilane + 4 NH(3).
-!- The enzyme works by stepwise addition of pyrrolylmethyl groups until a hexapyrrole is present at the active center. -!- The terminal tetrapyrrole is then hydrolyzed 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, 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. -!- Formerly EC 4.3.1.8.

UniProtKB Entries (1)

P06983
HEM3_ECOLI
Escherichia coli K-12
Porphobilinogen deaminase

PDB Structure

PDB 1AH5
External Links
Method X-RAY DIFFRACTION
Organism Escherichia
Primary Citation
Determination of the structure of seleno-methionine-labelled hydroxymethylbilane synthase in its active form by multi-wavelength anomalous dispersion.
Hadener, A., Matzinger, P.K., Battersby, A.R., McSweeney, S., Thompson, A.W., Hammersley, A.P., Harrop, S.J., Cassetta, A., Deacon, A., Hunter, W.N., Nieh, Y.P., Raftery, J., Hunter, N., Helliwell, J.R.
Acta Crystallogr.,Sect.D