NAD+ research centres on nicotinamide adenine dinucleotide, a pyridine dinucleotide coenzyme present in every mammalian cell that acts both as an electron carrier in central metabolism and as a consumed substrate for sirtuins, PARPs and CD38. This guide explains the coenzyme’s structure, biosynthetic routes, enzymatic consumers, published ageing literature, and the stability and handling behaviour that matters when NAD+ is prepared as a laboratory solution. Written for laboratory researchers; research use only.
Key takeaways
- NAD+ (CAS 53-84-9, C21H27N7O14P2, MW 663.4 g/mol) is a dinucleotide coenzyme, not a peptide — it contains no amide backbone of amino acids and behaves chemically like a nucleotide.
- It has two distinct roles in published biochemistry: a catalytic role as the NAD+/NADH redox couple, where it is regenerated, and a consumed role where the glycosidic bond is cleaved and nicotinamide is released.
- The main NAD+-consuming enzyme families described in the literature are the sirtuins (SIRT1–7), the poly(ADP-ribose) polymerases (PARP1/2), the ectoenzymes CD38 and CD157, and SARM1 in axons.
- Mammalian cells regenerate most of their NAD+ through the salvage pathway (nicotinamide → NMN via NAMPT → NAD+ via NMNAT), with de novo tryptophan and Preiss–Handler routes contributing less flux.
- NMN and nicotinamide riboside (NR) are precursors studied as ways of feeding that salvage pathway; Bieganowski and Brenner described the NR kinase route in 2004.
- Tissue NAD+ declines with age in several published rodent and human datasets; Camacho-Pereira and colleagues reported CD38 as a driver of that decline in 2016.
- In solution, NAD+ is comparatively acid-stable and base-labile, degrades faster with temperature, and is best prepared fresh and kept cold and dark — a 2024 Molecules study quantified buffer-dependent degradation of nicotinamide cofactors.
What is NAD+?
NAD+ is nicotinamide adenine dinucleotide in its oxidised form: two nucleotides — one carrying nicotinamide, one carrying adenine — joined tail-to-tail through a pyrophosphate bridge. It is a coenzyme, meaning it is not itself an enzyme but is required by hundreds of them, and it is present in every compartment of the mammalian cell that runs oxidative or glycolytic chemistry.
The compound sits in an unusual position among research materials sold as lyophilised vials. Almost everything else in a peptide catalogue is a chain of amino acids; NAD+ is a nucleotide derivative. That distinction is practical rather than academic, because it changes how the material dissolves, how it degrades and which analytical methods identify it credibly.
Its biological interest comes from a simple asymmetry described repeatedly in the literature. In its redox role NAD+ is conserved — reduced to NADH, re-oxidised, and used again. In its signalling role it is destroyed — a whole class of enzymes cleaves the bond between nicotinamide and ribose to power a chemical modification, and the cell must then rebuild the molecule. Verdin’s 2015 Science review framed the ageing literature around exactly this tension between supply and consumption.
NAD+ structure and specification
The specification below is drawn from PubChem and standard chemical catalogue data for the free acid form. Because NAD+ is commonly supplied as a disodium salt in some catalogues, molecular weight figures quoted elsewhere may differ; always read the identity section of the batch certificate rather than assuming a value.
| Property | Value | Note |
|---|---|---|
| Chemical name | β-Nicotinamide adenine dinucleotide, oxidised form | β-anomer is the biologically active configuration |
| CAS number | 53-84-9 | Free acid; salt forms carry separate CAS numbers |
| Molecular formula | C21H27N7O14P2 | Seven nitrogens across nicotinamide and adenine |
| Molecular weight | 663.4 g/mol | Used for molar solution preparation |
| Class | Pyridine dinucleotide coenzyme | Nucleotide chemistry, not peptide chemistry |
| Reduced partner | NADH | Absorbs strongly at 340 nm; NAD+ does not |
| Phosphorylated relative | NADP+ / NADPH | Extra 2′-phosphate; separate reductive-biosynthesis pool |
| Typical appearance | White to off-white lyophilised powder | Hygroscopic; equilibrate to room temperature before opening |
| Solubility | Freely water-soluble | Aqueous buffers preferred over organic solvents |
Redox coenzyme versus signalling substrate
NAD+ performs two chemically different jobs. As a redox coenzyme it accepts a hydride ion at position 4 of its nicotinamide ring to become NADH, then gives that hydride back — the molecule is not consumed. As a signalling substrate it is cleaved, releasing nicotinamide and donating an ADP-ribose unit, so the molecule is destroyed and must be resynthesised.
The redox role is the one described in every metabolism textbook. Glycolysis, the tricarboxylic acid pathway and fatty acid oxidation all reduce NAD+ to NADH, and the mitochondrial electron transport chain re-oxidises NADH at complex I. The ratio between the two forms, rather than the absolute amount, is what constrains flux through those routes.
The signalling role is the newer story and the reason NAD+ appears in ageing research at all. Because sirtuins and PARPs consume the coenzyme stoichiometrically, their activity is coupled to how much free NAD+ the compartment can supply. That coupling makes NAD+ availability a plausible node linking metabolic state to chromatin regulation and DNA repair, which is the argument Verdin advanced in 2015 and Covarrubias and colleagues expanded in their 2021 Nature Reviews Molecular Cell Biology review.
The NAD+-consuming enzymes
Four enzyme families dominate the NAD+ consumption literature: sirtuins, PARPs, the CD38/CD157 ectoenzymes and SARM1. Each cleaves NAD+ to release nicotinamide, and each uses the resulting ADP-ribose fragment for a different purpose — protein deacylation, poly-ADP-ribosylation, calcium-mobilising messenger synthesis or axonal signalling respectively.
Sirtuins
The seven mammalian sirtuins are NAD+-dependent deacylases distributed across the nucleus, cytoplasm and mitochondria. They strip acetyl and other acyl groups from lysine residues on histones and metabolic enzymes, and because the reaction spends one NAD+ per acyl group removed, sirtuin output is sensitive to how much free coenzyme the compartment holds. This is the mechanistic link most often invoked when NAD+ is discussed alongside metabolic regulation.
PARPs
PARP1 and PARP2 detect DNA strand breaks and respond by building branched chains of ADP-ribose on acceptor proteins. A single strand-break event can be expensive in NAD+ terms. Published work describes PARP hyperactivation as a route to compartmental NAD+ depletion, which is one of the mechanisms proposed to explain why genotoxic stress and NAD+ availability appear coupled.
CD38 and CD157
CD38 is a cell-surface glycohydrolase that turns NAD+ into cyclic ADP-ribose and related calcium-mobilising messengers. Camacho-Pereira and colleagues reported in Cell Metabolism in 2016 that CD38 expression rises with age in mice and that CD38-null animals were protected from age-related tissue NAD+ decline, with downstream effects on SIRT3 activity. It is one of the more direct pieces of evidence linking a specific consumer to the ageing phenotype.
SARM1
SARM1 is a NAD+-cleaving enzyme activated in injured axons. Its discovery reframed axon degeneration as an active, NAD+-consuming programme rather than passive decay, and it explains why NMN accumulation and NAD+ loss are measured together in neuronal injury models.
Biosynthesis, salvage and the NMN/NR precursors
Mammalian cells make NAD+ by three routes, but they rely overwhelmingly on one. The salvage pathway recaptures the nicotinamide released by consuming enzymes, converting it to nicotinamide mononucleotide (NMN) via NAMPT and then to NAD+ via the NMNAT enzymes. The de novo route from tryptophan and the Preiss–Handler route from nicotinic acid contribute smaller shares of total flux in most tissues.
NAMPT is the rate-limiting step of the salvage route, which is why it appears so often as an experimental handle. Feeding the pathway downstream of NAMPT — with NMN — or through a parallel entry point — with nicotinamide riboside, phosphorylated by the NRK enzymes described by Bieganowski and Brenner in Cell in 2004 — became the standard strategy for raising cellular NAD+ in preclinical work.
Trammell and colleagues reported in Nature Communications in 2016 that nicotinamide riboside raised blood NAD+ in mice and in a human pharmacokinetic study, which established NR as an orally available precursor. Rajman, Chwalek and Sinclair’s 2018 Cell Metabolism review catalogued the in vivo evidence across NAD+-boosting molecules and is the standard entry point to that literature.
| Precursor | Abbreviation | Entry point | Key enzyme | Research note |
|---|---|---|---|---|
| Tryptophan | Trp | De novo route | IDO / TDO, then QPRT | Amino acid starting point; low flux in most tissues |
| Nicotinic acid | NA | Preiss–Handler route | NAPRT | Distinct from nicotinamide despite similar naming |
| Nicotinamide | NAM | Salvage route | NAMPT (rate-limiting) | Released by every NAD+-consuming reaction |
| Nicotinamide mononucleotide | NMN | Downstream of NAMPT | NMNAT1–3 | One enzymatic step from NAD+ |
| Nicotinamide riboside | NR | Parallel salvage entry | NRK1 / NRK2 | Route described by Bieganowski and Brenner, 2004 |
What the ageing research literature reports
Published rodent and human datasets describe a decline in tissue NAD+ concentration with age across liver, muscle, brain and skin, though the magnitude varies by tissue and measurement method. The mechanistic explanations offered fall into two camps: reduced synthesis, typically attributed to falling NAMPT activity, and increased consumption, attributed largely to rising CD38 expression and chronic PARP activation.
Camacho-Pereira and colleagues provided one of the clearest experimental separations of those possibilities. Their 2016 work showed that CD38-deficient mice were protected from the age-associated NAD+ decline and from the associated mitochondrial changes, implicating consumption rather than synthesis as a dominant term in that model.
Rajman, Chwalek and Sinclair reviewed the in vivo evidence for NAD+-boosting molecules in 2018, and their assessment is worth repeating precisely because it is measured: the preclinical literature is broad and largely consistent, while translation to human outcomes remains an open programme. Covarrubias and colleagues reached a similar conclusion in 2021, adding inflammation-driven CD38 induction as a mechanistic candidate.
NAD+ stability, light, pH and temperature
NAD+ is one of the less forgiving research materials in solution. The oxidised form is comparatively stable in mildly acidic conditions and degrades noticeably faster as pH rises, while the reduced NADH form behaves in the opposite direction — stable in base, labile in acid. That inversion is the single most useful fact to hold when planning buffer conditions.
Wolfe and colleagues quantified long-term nicotinamide cofactor behaviour in common buffers in Molecules in 2024. They reported that Tris buffer preserved cofactor content markedly better than sodium phosphate or HEPES, and that a shift from 19 °C to 25 °C was enough to move NADH retention over 43 days from above 90 per cent to roughly 75 per cent. Temperature and buffer choice are therefore not incidental variables.
| Form | Condition | Practical guidance |
|---|---|---|
| Lyophilised powder, sealed vial | −20 °C, dark, desiccated | Most stable form; equilibrate to room temperature before opening to avoid condensation |
| Lyophilised powder, sealed vial | 2–8 °C, dark | Acceptable for shorter working periods; keep the desiccant with the vial |
| Aqueous solution | 2–8 °C, dark | Short working window only; prepare fresh for quantitative assays |
| Aqueous solution, aliquoted | −20 °C or below, dark | Single-use aliquots; avoid repeated thawing |
| Any solution | Room temperature, lit bench | Avoid — combines the two fastest degradation drivers |
| Buffered solution | Tris preferred over phosphate/HEPES | Reported in Wolfe et al., 2024; record the buffer used |
Solution preparation concentration reference
The table below is a concentration reference for preparing laboratory solutions from a lyophilised vial. It states only the relationship between the mass in the vial, the volume of diluent added, and the resulting concentration. It is not a dosing table and carries no implication of administration to any organism.
- Equilibrate. Bring the sealed vial from cold storage to room temperature before handling, so that condensation does not form on the cake.
- Select the diluent. For assay work, choose a buffer appropriate to the method; Tris at a mildly acidic to neutral pH performed best for cofactor retention in the published buffer comparison.
- Add diluent slowly. Direct the stream against the vial wall rather than onto the cake to reduce foaming and local shear.
- Dissolve gently. Swirl or roll; do not shake vigorously. NAD+ dissolves readily in water without agitation.
- Aliquot immediately. Split into single-use volumes in amber or foil-wrapped tubes before freezing.
- Label completely. Record compound, batch number, concentration, buffer, pH and preparation date on every aliquot.
| Diluent volume | Resulting concentration | Amount per 0.1 mL | Approximate molarity (MW 663.4) |
|---|---|---|---|
| 2 mL | 250 mg/mL | 25 mg | ≈ 377 mM |
| 5 mL | 100 mg/mL | 10 mg | ≈ 151 mM |
| 10 mL | 50 mg/mL | 5 mg | ≈ 75 mM |
| 25 mL | 20 mg/mL | 2 mg | ≈ 30 mM |
| 50 mL | 10 mg/mL | 1 mg | ≈ 15 mM |
Molarity figures are calculated from the free-acid molecular weight and rounded. If the batch certificate identifies a salt form, recalculate using the salt’s formula weight before reporting molar concentrations. Our reconstitution guide covers the general arithmetic in more detail.
Purity, identity and the certificate of analysis
Because NAD+ is a nucleotide rather than a peptide, its certificate of analysis reads slightly differently from a peptide COA. Identity is confirmed by mass spectrometry against the expected 663.4 monoisotopic-adjacent mass, and purity is typically reported by high-performance liquid chromatography with ultraviolet detection.
Two impurity classes are worth reading for. The first is nicotinamide and free adenine-side fragments, which indicate hydrolysis of the glycosidic or pyrophosphate bonds during synthesis, purification or storage. The second is NADH, which will show as a distinct chromatographic peak and can be cross-checked by ultraviolet absorbance at 340 nm — NAD+ does not absorb meaningfully there, so a 340 nm signal in a nominally oxidised preparation is informative.
GenoPept publishes a per-batch third-party certificate for each lot, with HPLC purity and mass spectrometry identity, at the COA certificates page. Match the batch number printed on the vial label to the certificate rather than relying on a generic specimen document. Our purity testing guide explains how to read chromatograms and mass spectra in detail.
What a good NAD+ certificate shows
Batch number matching the vial, HPLC purity with the chromatogram attached, mass spectrometry identity, appearance, water content where measured, and the test date. Anything undated or unbatched is not a certificate.
What it cannot tell you
A certificate describes the material as tested at the laboratory on the test date. It says nothing about how the vial was handled in transit or in your own storage, which is why the handling variables in Figure 4 remain yours to control.
NAD+ in the GenoPept store
Frequently asked questions
Is NAD+ a peptide?
No. NAD+ is a dinucleotide — two nucleotides joined by a pyrophosphate bridge — and contains no amino acids or peptide bonds. It is stocked alongside research peptides because it is supplied in the same lyophilised vial format and studied in overlapping metabolic literature, but its chemistry, solubility and degradation behaviour are those of a nucleotide.
What is the molecular weight of NAD+?
The free acid form has a molecular formula of C21H27N7O14P2 and a molecular weight of 663.4 g/mol, with CAS number 53-84-9. Salt forms, most commonly the disodium salt, have a higher formula weight and a different CAS number. Check the identity section of the batch certificate before calculating molar concentrations.
What is the difference between NAD+ and NADH?
They are the oxidised and reduced forms of the same coenzyme. NAD+ accepts a hydride ion at carbon 4 of its nicotinamide ring to become NADH, and the electron transport chain removes it again. Analytically, NADH absorbs strongly at 340 nm while NAD+ does not, which is the basis of most enzyme assays using the pair.
What is the difference between NAD+, NMN and NR?
NMN and nicotinamide riboside are precursors, not the coenzyme itself. NR is phosphorylated by NRK enzymes to NMN, and NMN is adenylylated by NMNAT enzymes to NAD+. Both are studied as ways of raising cellular NAD+ through the salvage pathway without depending on the rate-limiting NAMPT step.
Does NAD+ need to be refrigerated?
Sealed lyophilised NAD+ is most stable at −20 °C in the dark with desiccant, and refrigeration at 2–8 °C is acceptable for shorter working periods. Once in solution, the material should be kept cold, dark and ideally aliquoted for single use, because degradation accelerates with temperature and light exposure.
Why does NAD+ degrade so quickly in solution?
Two bonds are vulnerable: the glycosidic bond linking nicotinamide to its ribose, and the pyrophosphate bridge. Both hydrolyse faster as pH rises and as temperature increases. A 2024 buffer study reported that Tris preserved nicotinamide cofactors better than phosphate or HEPES, and that a six-degree temperature rise measurably reduced retention over weeks.
Which enzymes consume NAD+?
Four families dominate the literature: the sirtuins SIRT1–7, which use NAD+ for protein deacylation; PARP1 and PARP2, which build ADP-ribose chains during the DNA damage response; the CD38 and CD157 ectoenzymes, which generate calcium-mobilising messengers; and SARM1, which cleaves NAD+ in injured axons. Each releases free nicotinamide.
Is NAD+ legal to buy in the UK for research?
NAD+ is not a controlled drug under the Misuse of Drugs Act 1971 and is supplied in the UK as a laboratory research chemical, not as a medicine. It must not be marketed or supplied for human use. Purchasers should be qualified researchers or institutions. This is general information, not legal advice.
References
- Verdin E. NAD+ in aging, metabolism, and neurodegeneration. Science. 2015;350(6265):1208–1213. PubMed
- Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology. 2021;22(2):119–141. PubMed
- Rajman L, Chwalek K, Sinclair DA. Therapeutic potential of NAD-boosting molecules: the in vivo evidence. Cell Metabolism. 2018;27(3):529–547. PubMed
- Camacho-Pereira J, Tarragó MG, Chini CCS, et al. CD38 dictates age-related NAD decline and mitochondrial dysfunction through an SIRT3-dependent mechanism. Cell Metabolism. 2016;23(6):1127–1139. PubMed
- Bieganowski P, Brenner C. Discoveries of nicotinamide riboside as a nutrient and conserved NRK genes establish a Preiss-Handler independent route to NAD+ in fungi and humans. Cell. 2004;117(4):495–502. PubMed
- Trammell SAJ, Schmidt MS, Weidemann BJ, et al. Nicotinamide riboside is uniquely and orally bioavailable in mice and humans. Nature Communications. 2016;7:12948. Nature Communications
- Wolfe KD, Alahuhta M, Himmel ME, Bomble YJ, Jennings GK, Cliffel DE. Long-term stability of nicotinamide cofactors in common aqueous buffers: implications for cell-free biocatalysis. Molecules. 2024;29(22):5453. DOI
Research-grade NAD+, batch-verified
GenoPept supplies NAD+ as a lyophilised vial with a per-batch third-party certificate of analysis covering HPLC purity and mass spectrometry identity, dispatched from the UK, strictly for laboratory research.