Nicotinic acid phosphoribosyl transferase

Figure 8.2. Synthesis of NAD from nicotinamide, nicotinic acid, and qninolinic acid. Quinolinate phosphoribosyltransferase, EC 2.4.2.19 nicotinic acid phosphoribosyl-transferase, EC 2.4.2.11 nicotinamide phosphoribosyltransferase, EC 2.4.2.12 nicotinamide deamidase, EC 3.5.1.19 NAD glycohydrolase, EC 3.2.2.S NAD pyrophosphatase, EC 3.6.1.22 ADP-ribosyltransferases, EC 2.4.2.31 and EC 2.4.2.36 and poly(ADP-ribose) polymerase, EC 2.4.2.30. PRPP, phosphoribosyl pyrophosphate.

Figure 11.9. ISAD synthesis pathway from nicotinamide or niacin (l)nicoti-namidase (E.C. 3.5.1.19) (2)nicotinamide phosphoribosyl transferase, which requires ATP (3)1SIMN adenyl transferase, which requires ATP (4) nicotinic acid phosphoribosyl transferase, which requires ATP (5) NMN adenyl transferase, which requires ATP (6) NAD synthetase, which requires ATP. Ri, ribose P, phosphate Ad, adenine NMN, nicotinamide mononucleotide. This figure is from Ref 33 and is used with permission.

Quinolinic acid phosphoribosyl transferase (PT) catalyzes the formation of nicotinic acid mononucleotide (NaMN) from quinolinic acid and phosphoribosyl pyrophosphate. The pyridine nucleotide NaMN reacts with ATP (adenosine Hiphos-phate) upon mediation of NaMN adenylyltransferase to form the nicotinic acid adenine dinucleotide (NaAD) (Figure 6.7). The latter is converted to NAD by NAD synthetase. NADP is formed from NAD by the catalysis of NAD kinase. 

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