Quinolinate synthase (, NadA, QS, quinolinate synthetase) is an enzyme with systematic name glycerone phosphate:iminosuccinate alkyltransferase (cyclizing). This enzyme catalyses the following chemical reaction
This iron-sulfur protein requires a [4Fe-4S] cluster for activity. The quinolinic acid is later incorporated into nicotinamide adenine dinucleotide.