Quinolinate phosphoribosyl transferase (QPRTase) ornicotinate-nucleotide pyrophosphorylase EC:2.4.2.19 is involvedin the de novo synthesis of NAD in both prokaryotes andeukaryotes. It catalyses the reaction of quinolinic acid with5-phosphoribosyl-1-pyrophosphate (PRPP) in the presence of Mg2+to give rise to nicotinic acid mononucleotide (NaMN),pyrophosphate and carbon dioxide [1,2]. The QA substrate isbound between the C-terminal domain of one subunit, and theN-terminal domain of the other. The N-terminal domain has analpha/beta hammerhead fold.