NAD from aspartate

Route: Aspartate → Iminoaspartate + Dihydroxyacetone phosphate → Quinolinate + 5-Phosphoribosyl 1-pyrophosphate → Nicotinate mononucleotide → Nicotinic acid adenine dinucleotide (deamido-NAD) → Nicotinamide adenine dinucleotide

This is a dominant route to NAD in bacteria. L-Aspartate oxidase removes two hydrogens from aspartate and gives iminoaspartate; in cells without oxygen it passes the electrons to fumarate, and with oxygen it can pass them to oxygen. Quinolinate synthase joins iminoaspartate to dihydroxyacetone phosphate and closes the pyridine ring of quinolinate. Quinolinate phosphoribosyltransferase attaches the ribose phosphate of PRPP and releases CO₂, which gives nicotinate mononucleotide. An adenylyltransferase adds AMP from ATP to make nicotinic acid adenine dinucleotide, and NAD synthetase turns the carboxyl group into an amide with ammonia, using a second ATP. In eukaryotes, de novo NAD synthesis begins with tryptophan and is also called the kynurenine pathway.

Practice this pathway All pathways

Steps

Enzyme names and EC numbers are those used on the interactive board. Checked against sources: see the claim table in the repository (tools/pathway_data/checks).