CATH Classification

Domain Context

CATH Clusters

Superfamily Porphobilinogen deaminase, C-terminal domain
Functional Family Porphobilinogen deaminase, putative

Enzyme Information

2.5.1.61
Hydroxymethylbilane synthase.
based on mapping to UniProt P08397
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)

P08397
HEM3_HUMAN
Homo sapiens
Porphobilinogen deaminase

PDB Structure

PDB 3ECR
External Links
Method X-RAY DIFFRACTION
Organism
Primary Citation
Structural insight into acute intermittent porphyria.
Song, G., Li, Y., Cheng, C., Zhao, Y., Gao, A., Zhang, R., Joachimiak, A., Shaw, N., Liu, Z.J.
Faseb J.