Buy NAD+

What is NAD+?

NAD+ (nicotinamide adenine dinucleotide, oxidized form) is a dinucleotide coenzyme — not a peptide — composed of an adenosine monophosphate unit joined to nicotinamide mononucleotide through a phosphoanhydride bond. Molecular formula C21H27N7O14P2, molecular weight 663.4 Da, CAS 53-84-9. It contains no amino acids and no peptide bonds, and it is listed alongside research peptides here only because the metabolic questions it answers overlap with theirs.

The molecule does two jobs that are easy to conflate. As a redox carrier it accepts a hydride from glycolysis and the citric acid cycle, becoming NADH, then hands those electrons to Complex I of the electron transport chain and cycles back to NAD+. In that role it is a catalyst — recycled, not consumed. As a signalling substrate it is destroyed: sirtuins, PARPs and CD38 cleave the glycosidic bond and release nicotinamide, which means every deacylation reaction and every ADP-ribosylation event permanently removes an NAD+ molecule from the pool. The whole field of NAD+ decline research follows from that second fact.

One practical difference deserves stating up front, because it catches people who have only handled peptides. Reconstituted NAD+ solutions degrade considerably faster than reconstituted peptide solutions. Where a lyophilized peptide gives you 14 to 28 days at 2–8°C, NAD+ in solution should be used within 24 to 48 hours — it hydrolyses at the glycosidic and pyrophosphate bonds, and alkaline pH accelerates the process sharply. Prepare it fresh, in the volume the experiment needs, and do not treat a leftover vial as a stock.

How Does NAD+ Work? Mechanism of Action

Start with the redox function, because it sets the ceiling on everything else. NAD+ accepts electrons as NADH at three points in the citric acid cycle and one in glycolysis, then donates them at Complex I, feeding the proton gradient that ATP synthase converts into ATP. What matters biologically is not the absolute amount of NAD+ but the NAD+/NADH ratio — a cell with plenty of total nicotinamide dinucleotide but a reduced ratio cannot run oxidative metabolism, because the oxidized form is what the dehydrogenases need.

The signalling function is where the aging literature sits. Sirtuins — SIRT1 through SIRT7 — are NAD+-dependent deacylases that strip acetyl and other acyl groups from lysine residues on histones and transcription factors. SIRT1 acting on PGC-1alpha and the FOXO family governs mitochondrial biogenesis and stress-resistance programmes; SIRT3 does related work inside the mitochondrial matrix. Because these enzymes consume NAD+ stoichiometrically rather than using it catalytically, sirtuin activity is directly limited by NAD+ availability, and the Km values sit close enough to physiological concentrations that a falling pool translates into falling activity rather than being buffered away.

Two other consumers compete for the same pool. PARP1 and PARP2 use NAD+ for poly-ADP-ribosylation during the DNA damage response, and PARP1 in particular can drain cellular NAD+ rapidly when damage is extensive — an established route by which genotoxic stress suppresses sirtuin activity indirectly. CD38, an ectoenzyme that increases with age and inflammation, hydrolyses both NAD+ and its precursor NMN. Against these, NAMPT (nicotinamide phosphoribosyltransferase) runs the salvage pathway that recycles nicotinamide back into NMN and then into NAD+, and NAMPT is the rate-limiting step in that recovery.

The honest gap: whether intact NAD+ crosses the plasma membrane is disputed. A substantial body of work indicates that extracellular NAD+ is hydrolysed by CD73 and CD38 to nicotinamide riboside and nicotinamide before uptake, meaning that what enters the cell is a precursor rather than the dinucleotide itself. That is a real mechanistic controversy, not a technicality — it changes how an experiment adding NAD+ to a culture medium should be interpreted, and it is the strongest argument for including a precursor comparison arm in any study design.

Research Applications of NAD+

Sirtuin and Epigenetic Research

• Sirtuin deacylase activity assays: fluorogenic substrate turnover measured against NAD+ concentration, which gives a direct dose-response rather than an inferred one.
• PGC-1alpha and FOXO acetylation state: immunoprecipitation followed by acetyl-lysine blotting, linking NAD+ availability to a transcriptional programme.
• Mitochondrial biogenesis endpoints: mitochondrial DNA copy number and TFAM expression downstream of SIRT1 and SIRT3 activity.

DNA Repair and PARP Biology

• PARP1 activation models: poly-ADP-ribose accumulation after genotoxic insult, with NAD+ depletion measured in parallel to show the competition directly.
• NAD+ pool quantification: enzymatic cycling assays or LC-MS/MS for NAD+ and NADH separately, since the ratio carries the information rather than the total.
• CD38 activity studies: the ectoenzyme that consumes both NAD+ and NMN and rises with age, relevant whenever a model involves inflammatory tissue.

Mitochondrial and Metabolic Models

• Complex I function: NADH-linked respiration measured against succinate-linked respiration to separate substrate supply from chain capacity.
• Salvage pathway characterization: NAMPT expression and activity, the rate-limiting step that determines how fast a depleted pool recovers.
• Combined signalling and substrate designs: NAD+ paired with MOTS-c, where AMPK activation raises NAMPT expression and the substrate question becomes explicit.

NAD+ vs NMN (Nicotinamide Mononucleotide)

Feature	NAD+	NMN
Identity	The active dinucleotide coenzyme	Immediate biosynthetic precursor to NAD+
Molecular formula	C21H27N7O14P2	C11H15N2O8P
Molecular weight	663.4 Da	334.2 Da
Structure	Two nucleotides joined by a pyrophosphate bond	Single nucleotide
Conversion step	None — already the active form	Requires NMNAT1/2/3 to become NAD+
Cell entry	Disputed; largely degraded extracellularly to precursors	Enters via precursor transport routes, including Slc12a8 in some tissues
Direct sirtuin substrate	Yes	No — must be converted first
Solution stability	Poor: use within 24–48 hours	Better, but still shorter-lived than a peptide solution
Research use	Direct substrate supply and enzymology	Precursor flux and salvage pathway studies

The choice is not about which is stronger. NAD+ is what the enzymes actually use, so it is the right reagent for enzymology where substrate concentration must be known. NMN is the right reagent when the question is whether a cell can build its own pool through the salvage pathway. Substituting one for the other silently changes what the experiment measures.

NAD+ Technical Specifications

Compound Name	NAD+ (nicotinamide adenine dinucleotide, oxidized form)
Common Synonyms	Nicotinamide adenine dinucleotide, NAD plus, beta-NAD, coenzyme I, DPN
Classification	Dinucleotide redox coenzyme — not a peptide
CAS Number	53-84-9
Molecular Formula	C21H27N7O14P2
Molecular Weight	663.4 Da
Structural Components	Adenosine monophosphate linked to nicotinamide mononucleotide via a phosphoanhydride bond
Reduced Form	NADH
Consuming Enzymes	Sirtuins (SIRT1-7), PARP1/2, CD38
Salvage Pathway Enzyme	NAMPT (nicotinamide phosphoribosyltransferase), rate-limiting
Purity	≥99% by HPLC
Purity Confirmation	LC-MS/MS molecular weight verification
Endotoxin Testing	LAL (Limulus Amebocyte Lysate) method
Physical Form	Lyophilized powder
Appearance	White to off-white powder
Reconstitution	Sterile water for injection preferred; bacteriostatic water acceptable where multi-access is required
Storage (lyophilized)	-20°C, desiccated, protected from light
Storage (reconstituted)	2–8°C, use within 24–48 hours — considerably shorter than a peptide solution
pH Sensitivity	Degrades rapidly at alkaline pH; keep preparations near neutral or slightly acidic
Shelf Life	24 months from manufacture (lyophilized)
Testing Methods	HPLC, LC-MS/MS, LAL Endotoxin
Documentation	Certificate of Analysis (CoA) per batch
FDA Status	Not approved as an injectable drug product
Intended Use	In-vitro laboratory research only

How to Reconstitute NAD+ for Research

Treat NAD+ as a same-week reagent, not a stock solution. The lyophilized powder is stable for two years at -20°C, but once it meets water the clock runs in hours rather than weeks: hydrolysis at the glycosidic and pyrophosphate bonds proceeds steadily at 4°C and accelerates sharply above neutral pH. Reconstitute the amount an experiment needs, use it within 24–48 hours, and if a study spans several days, prepare fresh each day rather than drawing from one vial. Researchers coming from peptide work are the ones most likely to get this wrong, because 14–28 days is the number their instincts supply.

1. Bring the vial to room temperature before opening, and plan the volume around what will be consumed in the next 24–48 hours rather than the vial size.
2. Use sterile water for injection where the preparation will be used once. Bacteriostatic water is acceptable when a vial genuinely needs multiple accesses, but the short solution life means the preservative advantage rarely comes into play.
3. Swab the septum with 70% isopropyl alcohol and allow 30 seconds to dry.
4. Inject the diluent slowly against the inner vial wall. For a 500 mg vial, 5 mL yields 100 mg/mL; 10 mL yields 50 mg/mL. At 663.4 Da, 50 mg/mL is approximately 75 mM.
5. Swirl gently until fully dissolved. NAD+ dissolves readily in water; the solution may carry a faint yellow cast, which is normal at higher concentrations.
6. Check the pH of any buffered working dilution. Alkaline conditions degrade NAD+ quickly, so a buffer above pH 8 will cost you material before the assay starts.
7. Label with the reconstitution date and time — not just the date. A 24–48 hour window makes the hour matter.
8. Store at 2–8°C, protected from light, and use within 24–48 hours. Discard rather than salvaging leftovers for a later run.

Regulatory status: NAD+ is not approved by the FDA as an injectable drug product and is not a scheduled substance. Nicotinamide-based precursors are regulated separately as dietary ingredients, which is a different category and should not be read as approval of NAD+ itself. NAD+ is not named on the WADA Prohibited List. Sold by Peptide.Express for in-vitro laboratory research use only.

Research References

1. NAD+ metabolism, sirtuin biology and PARP-mediated depletion literature in aging models. Presented as a search: the field is large, fast-moving, and no single review covers the redox, signalling and decline arms adequately. Search PubMed for NAD+ sirtuin and PARP aging studies
2. NAMPT salvage pathway and NAD+ precursor literature, covering the CD38 and CD73 extracellular degradation question that bears on whether intact NAD+ enters cells. Search PubMed for NAMPT salvage pathway and CD38 studies
3. FDA drug approvals and databases. NAD+ does not appear as an approved injectable drug product; nicotinamide-based compounds are regulated in other categories. Search the FDA drug approval databases

All products are sold for in-vitro laboratory research use only. Not intended for human consumption, clinical use, or veterinary use.