Phosphoribosylformylglycinamidine cyclo-ligase

In enzymology, a phosphoribosylformylglycinamidine cyclo-ligase is an enzyme that catalyzes the chemical reaction


 * ATP + 2-(formamido)-N1-(5-phospho-D-ribosyl)acetamidine $$\rightleftharpoons$$ ADP + phosphate + 5-amino-1-(5-phospho-D-ribosyl)imidazole

Thus, the two substrates of this enzyme are ATP and 2-(formamido)-N1-(5-phospho-D-ribosyl)acetamidine, whereas its 3 products are ADP, phosphate, and 5-amino-1-(5-phospho-D-ribosyl)imidazole.

This enzyme belongs to the family of ligases, specifically the cyclo-ligases, which form carbon-nitrogen bonds. The systematic name of this enzyme class is 2-(formamido)-N1-(5-phosphoribosyl)acetamidine cyclo-ligase (ADP-forming). Other names in common use include phosphoribosylaminoimidazole synthetase, AIR synthetase, 5'-aminoimidazole ribonucleotide synthetase, 2-(formamido)-1-N-(5-phosphoribosyl)acetamidine cyclo-ligase, and (ADP-forming). This enzyme participates in purine metabolism.

Structural studies
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes, , , and.