Toward understanding the mechanism of the complex cyclization reaction catalyzed by imidazole glycerolphosphate synthase: crystal structures of a ternary complex and the free enzyme

Comparison of the free, acivicin-, and 6-diazo-5-oxo-L-norleucine inactivated crystal structures of the glutaminase active site shows structural changes accompanying activation of the imidazole glycerolphosphate synthase. Furthermore, the N(sup)1-(5'-phosphoribulosyl)-formimino-5-aminoimidazole-4-carboxamide ribonucleotide-bound and -free forms of the enzyme suggest crosstalk between active sites.