Allantoicase Explained

allantoicase
Ec Number:3.5.3.4
Cas Number:9025-21-2
Go Code:0004037
Width:270
Symbol:Allantoicase
Allantoicase
Pfam:PF03561
Pfam Clan:CL0202
Interpro:IPR015908
Scop:1sg3

Allantoicase is an enzyme that in humans is encoded by the ALLC gene. Allantoicase catalyzes the chemical reaction

allantoate + H2O

\rightleftharpoons

(S)-ureidoglycolate + urea

Thus, the two substrates of this enzyme are allantoate and H2O, whereas its two products are (S)-ureidoglycolate and urea.

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.

Structural studies

As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and .

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.[1] Each jelly-roll motif has two conserved surface patches that probably constitute the active site.[2]

Further reading

Notes and References

  1. 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 . Crystal structure of an allantoicase (YIR029W) from Saccharomyces cerevisiae at 2.4 A resolution . Proteins . 56 . 3 . 619–24 . August 2004 . 15229895 . 10.1002/prot.20164 . 5688375 . free .
  2. Leulliot N, Quevillon-Cheruel S, Sorel I, Graille M, Meyer P, Liger D, Blondeau K, Janin J, van Tilbeurgh H . Crystal structure of yeast allantoicase reveals a repeated jelly roll motif . The Journal of Biological Chemistry . 279 . 22 . 23447–52 . May 2004 . 15020593 . 10.1074/jbc.M401336200 . free .