Allantoicase (IPR005164)

Short name: Allantoicase

Overlapping homologous superfamilies

Family relationships



Allantoicase (also known as allantoate amidinohydrolase) is involved in purine degradation, facilitating the utilization of purines as secondary nitrogen sources under nitrogen-limiting conditions. While purine degradation converges to uric acid in all vertebrates, its further degradation varies from species to species. Uric acid is excreted by birds, reptiles, and some mammals that do not have a functional uricase gene, whereas other mammals produce allantoin. Amphibians and microorganisms produce ammonia and carbon dioxide using the uricolytic pathway. Allantoicase performs the second step in this pathway catalyzing the conversion of allantoate into ureidoglycolate and urea.

allantoate + H(2)0 = (S)-ureidoglycolate + urea

The structure of allantoicase is best described as being composed of two repeats (the allantoicase repeats: AR1 and AR2), which are connected by a flexible linker. The crystal structure, resolved at 2.4A resolution, reveals that AR1 has a very similar fold to AR2, both repeats being jelly-roll motifs, composed of four-stranded and five-stranded antiparallel beta-sheets [PMID: 15229895]. Each jelly-roll motif has two conserved surface patches that probably constitute the active site [PMID: 15020593].

The mammalian proteins matched by this entry are thought to be non-functional as mammals do not appear to possess allantoicase activity [PMID: 11054555].

GO terms

Biological Process

GO:0000256 allantoin catabolic process

Molecular Function

GO:0004037 allantoicase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.