2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase

{{Short description|Class of enzymes}}

{{Infobox protein family

| Symbol = OHCU_decarbox

| Name = OHCU decarboxylase

| image =

| width =

| caption = structure of ohcu decarboxylase from zebrafish

| Pfam = PF09349

| Pfam_clan =

| InterPro = IPR018020

| SMART =

| PROSITE =

| MEROPS =

| SCOP =

| TCDB =

| OPM family =

| OPM protein =

| CAZy =

| CDD =

}}

In molecular biology 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase (OHCU decarboxylase) {{EC number|4.1.1.n1}} is an enzyme involved in purine catabolism. It catalyses the decarboxylation of 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) into S(+)-allantoin.{{cite journal |vauthors=Ramazzina I, Folli C, Secchi A, Berni R, Percudani R | title = Completing the uric acid degradation pathway through phylogenetic comparison of whole genomes | journal = Nat. Chem. Biol. | volume = 2 | issue = 3 | pages = 144–8 |date=March 2006 | pmid = 16462750 | doi = 10.1038/nchembio768 | s2cid = 13441301 }}{{cite journal|vauthors=Cendron L, Berni R, Folli C, Ramazzina I, Percudani R, Zanotti G| title=The structure of 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase provides insights into the mechanism of uric acid degradation. | journal=J Biol Chem | year= 2007 | volume= 282 | issue= 25 | pages= 18182–9 | pmid=17428786 | doi=10.1074/jbc.M701297200 | doi-access=free | hdl=11577/1777398 | hdl-access=free }} It is the third step of the conversion of uric acid (a purine derivative) to allantoin. Step one is catalysed by urate oxidase and step two is catalysed by hydroxyisourate hydrolase.{{cite journal|vauthors=Kim K, Park J, Rhee S| title=Structural and functional basis for (S)-allantoin formation in the ureide pathway. | journal=J Biol Chem | year= 2007 | volume= 282 | issue= 32 | pages= 23457–64 | pmid=17567580 | doi=10.1074/jbc.M703211200 | doi-access=free }}{{cite journal|vauthors=Todd CD, Tipton PA, Blevins DG, Piedras P, Pineda M, Polacco JC| title=Update on ureide degradation in legumes. | journal=J Exp Bot | year= 2006 | volume= 57 | issue= 1 | pages= 5–12 | pmid=16317038 | doi=10.1093/jxb/erj013 | doi-access=free }}