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 Q43316
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)

Q43316
HEM3_ARATH
Arabidopsis thaliana
Porphobilinogen deaminase, chloroplastic

PDB Structure

PDB 4HTG
External Links
Method X-RAY DIFFRACTION
Organism
Primary Citation
Insights into the mechanism of pyrrole polymerization catalysed by porphobilinogen deaminase: high-resolution X-ray studies of the Arabidopsis thaliana enzyme.
Roberts, A., Gill, R., Hussey, R.J., Mikolajek, H., Erskine, P.T., Cooper, J.B., Wood, S.P., Chrystal, E.J., Shoolingin-Jordan, P.M.
Acta Crystallogr.,Sect.D