Phosphoribosylaminoimidazolesuccinocarboxamide synthase

In enzymology, a phosphoribosylaminoimidazolesuccinocarboxamide synthase is an enzyme that catalyzes the chemical reaction


 * ATP + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate + L-aspartate $$\rightleftharpoons$$ ADP + phosphate + (S)-2-[5-amino-1-(5-phospho-D-ribosyl)imidazole-4- carboxamido]succinate

The 3 substrates of this enzyme are ATP, 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate, and L-aspartate, whereas its 4 products are ADP, phosphate, (S)-2-[5-amino-1-(5-phospho-D-ribosyl)imidazole-4-, and carboxamido]succinate.

This enzyme belongs to the family of ligases, specifically those forming carbon-nitrogen bonds as acid-D-amino-acid ligases (peptide synthases). The systematic name of this enzyme class is 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate:L-aspartate ligase (ADP-forming). Other names in common use include phosphoribosylaminoimidazole-succinocarboxamide synthetase, PurC, SAICAR synthetase, 4-(N-succinocarboxamide)-5-aminoimidazole synthetase, 4-[(N-succinylamino)carbonyl]-5-aminoimidazole ribonucleotide, synthetase, SAICARs, phosphoribosylaminoimidazolesuccinocarboxamide synthetase, and 5-aminoimidazole-4-N-succinocarboxamide ribonucleotide synthetase. This enzyme participates in purine metabolism.

Structural studies
As of late 2007, 10 structures have been solved for this class of enzymes, with PDB accession codes, , , , , , , , , and.