This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in linear amidines. The systematic name of this enzyme class is allantoate amidinohydrolase. This enzyme participates in purine metabolism by 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.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 1O59 and 1SG3.
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 antiparallelbeta-sheets. Each jelly-roll motif has two conserved surface patches that probably constitute the active site.
^Xu Q, Schwarzenbacher R, Page R, Sims E, Abdubek P, Ambing E, Biorac T, Brinen LS, Cambell J, Canaves JM, Chiu HJ, Dai X, Deacon AM, DiDonato M, Elsliger MA, Floyd R, Godzik A, Grittini C, Grzechnik SK, Hampton E, Jaroszewski L, Karlak C, Klock HE, Koesema E, Kovarik JS, Kreusch A, Kuhn P, Lesley SA, Levin I, McMullan D, McPhillips TM, Miller MD, Morse A, Moy K, Ouyang J, Quijano K, Reyes R, Rezezadeh F, Robb A, Spraggon G, Stevens RC, van den Bedem H, Velasquez J, Vincent J, von Delft F, Wang X, West B, Wolf G, Hodgson KO, Wooley J, Wilson IA (August 2004). "Crystal structure of an allantoicase (YIR029W) from Saccharomyces cerevisiae at 2.4 A resolution". Proteins. 56 (3): 619–24. doi:10.1002/prot.20164. PMID15229895. S2CID5688375.
Florin M, Duchateau-Bosson G (1940). "Microdosage photometrique de l'allantoine en solutions pures et dans l'urine". Enzymologia. 9: 5–9.
Trijbels F, Vogels GD (May 1966). "Allantoicase and ureidoglycolase in Pseudomonas and Penicillium species". Biochimica et Biophysica Acta (BBA) - Enzymology and Biological Oxidation. 118 (2): 387–95. doi:10.1016/S0926-6593(66)80047-4. PMID4960174.
Hildebrand F, van Griensven M, Giannoudis P, Schreiber T, Frink M, Probst C, Grotz M, Krettek C, Pape HC (2005). "Impact of hypothermia on the immunologic response after trauma and elective surgery". Surgical Technology International. 14: 41–50. PMID16525953.
Gravenmade EJ, Vogels GD, Van der Drift C (March 1970). "Hydrolysis, racemization and absolute configuration of ureidoglycolate, a substrate of allantoicase". Biochimica et Biophysica Acta (BBA) - Enzymology. 198 (3): 569–82. doi:10.1016/0005-2744(70)90134-8. PMID4314237.