A practical reference on NADH: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Nicotinamide adenine dinucleotide, commonly abbreviated NAD+, is a coenzyme present in all living cells. The molecule consists of two nucleotides linked by phosphate groups, with adenine and a nicotinamide ring as its principal features. In its oxidized form, the nicotinamide ring can accept a hydride ion, becoming NADH. This reversible conversion places NAD+ at the center of many electron-transfer reactions. Its role as a redox carrier is well established across bacteria, plants, fungi, and animals.
Beyond redox chemistry, NAD+ acts as a substrate for several enzyme families. ADP-ribosyltransferases, sirtuins, and CD38 ectoenzymes cleave the molecule into nicotinamide and ADP-ribose or related products. These reactions connect NAD+ availability to processes such as DNA repair, chromatin modification, and calcium signaling. Because the coenzyme is used in both electron transfer and signaling, cells maintain separate pools in compartments including the cytosol, mitochondria, and nucleus. The relative sizes and regulation of those pools remain active areas of study.
Cells produce NAD+ through several biosynthetic routes. The salvage pathway recycles nicotinamide, while the Preiss-Handler pathway uses nicotinic acid, and a de novo route can start from tryptophan in some organisms. In mammals, the salvage pathway is generally considered the main source under ordinary conditions. Tissue concentrations vary widely by cell type and compartment, and measured declines with age have been reported in some studies. Whether such changes drive aging or mainly accompany it remains an open question.
In glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation, NAD+ is reduced to NADH at specific dehydrogenase steps. NADH then delivers electrons to the mitochondrial electron transport chain, mainly at complex I, supporting oxidative phosphorylation and ATP production. The balance between NAD+ and NADH, often expressed as a ratio, influences metabolic flux and redox homeostasis in different cellular compartments. Cytosolic and mitochondrial pools are connected but not identical, and their ratios can differ substantially because of compartment-specific enzymes and transport systems.
Beyond redox chemistry, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer its ADP-ribose moiety or remove acetyl groups. Sirtuins consume NAD+ during deacetylation, poly(ADP-ribose) polymerases use it in DNA damage responses, and CD38 enzymes hydrolyze it to signaling metabolites. These consumption pathways mean that NAD+ availability can influence gene regulation, DNA repair, and calcium signaling. Cellular NAD+ concentrations decline in some tissues with age in animal models, but whether this decline is a cause or consequence of aging in humans remains an active open question.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C21H27N7O14P2 | Oxidized free acid form; charge depends on pH. |
| Molar mass | 663.43 g/mol | Calculated for the free acid. |
| CAS Registry Number | 53-84-9 | For the anhydrous free acid; salts have different identifiers. |
| Appearance | White to off-white powder | Solid material; hygroscopic. |
| Solubility | Water-soluble | Dissolves in aqueous buffers; solubility varies with pH and salt. |
Beyond electron transfer, NAD+ serves as a substrate for enzymes that cleave it and attach its ADP-ribose portion to other molecules. This group includes poly(ADP-ribose) polymerases, CD38, and sirtuins. Such reactions consume NAD+ and can influence its availability for metabolism. Cells replenish NAD+ through a salvage pathway that recycles nicotinamide and through routes starting from tryptophan or vitamin B3 forms. How these synthesis and consumption routes are coordinated across tissues remains an active area of study, and compartment-specific concentrations are difficult to measure directly.
Nicotinamide adenine dinucleotide, abbreviated NAD+, is a dinucleotide built from adenine, nicotinamide, two ribose sugars, and two phosphate groups. The oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, is neutral. This pair acts as a reversible electron carrier in cells. NAD+ is present in bacteria, plants, animals, and fungi. Its structure allows it to accept and donate electrons without being consumed in the reactions it supports.
In redox reactions, NAD+ accepts a hydride ion, which consists of two electrons and one proton. The hydride adds to the nicotinamide ring at a specific carbon, converting NAD+ into NADH. Dehydrogenase enzymes use this step in glycolysis, the citric acid cycle, and fatty acid oxidation. NADH later donates electrons to the mitochondrial electron transport chain, helping to drive ATP synthesis. The balance between NAD+ and NADH reflects the metabolic state of a cell, and shifts in that balance can alter how pathways operate.
Biosynthesis of NAD+ starts from nicotinamide, nicotinic acid, or nicotinamide riboside through salvage pathways. A rate-limiting enzyme, nicotinamide phosphoribosyltransferase, converts nicotinamide to nicotinamide mononucleotide. Further coupling with ATP yields NAD+. In mammals, the liver and muscle can synthesize NAD+ from dietary precursors, but tissue levels vary widely. Researchers study these pathways to understand age-related changes, metabolic disorders, and neurodegeneration. Direct causal links between NAD+ decline and disease remain an active area of investigation.
NAD+ is a dinucleotide composed of adenine, ribose, and nicotinamide groups joined by phosphate linkages. It serves as a coenzyme in oxidoreductase reactions, cycling between oxidized NAD+ and reduced NADH. The molecule is water-soluble and occurs in all living cells. Its nicotinamide ring accepts hydride ions during catabolic reactions, linking substrate oxidation to electron transport. This redox couple supports ATP production and helps maintain cytosolic and mitochondrial redox balance in many cell types.
Laboratory handling of NAD+ follows standard practices for hygroscopic fine chemicals. Personnel typically avoid inhalation and skin contact, use gloves and eye protection, and work in a ventilated area. Quality control may include ultraviolet absorbance at the nicotinamide maximum, chromatographic purity, water content, and identity confirmation by mass spectrometry. Because commercial preparations can contain counterions, residual solvents, or related nucleotides, a certificate of analysis helps verify the material. Researchers should confirm that the form supplied matches the intended assay.
Measuring NAD+ in biological samples requires care because the molecule is chemically reactive and present at low concentrations in some tissues. Common approaches include enzymatic cycling assays, high-performance liquid chromatography, and liquid chromatography coupled to mass spectrometry. Each method has different sensitivity and specificity, and sample preparation can affect results. Acidic or alkaline extraction steps are used in some protocols, but the choice depends on the analyte and matrix. No single method is universally optimal for every tissue or fluid.
Solid NAD+ is relatively stable when kept dry, cold, and protected from light. Aqueous solutions are more vulnerable to hydrolysis and can lose activity during repeated freeze-thaw cycles or prolonged storage at ambient temperature. Stability depends on pH, ionic strength, and the presence of degrading enzymes or metal ions. For many laboratory uses, aliquots are stored frozen and thawed only once. Exact degradation rates vary by matrix, so stability should be checked for each application rather than assumed.
== Members == Graeme Naysmith – guitar (1987–1996; died 2024) Chris Cooper – drums, percussion (1987–1996) Ian Masters – vocals, bass (1987–1993) Ashley Horner – guitar (1989) Meriel Barham – vocals, guitar (1990–1995) Colleen Browne – bass, vocals (1992–1995)
== Business == George Batten (1854–1918), advertising executive whose firm was part of the merger that created what is now BBDO Clarence Birdseye (1886–1956), inventor, entrepreneur and naturalist who is considered to be the founder of the modern frozen food industry John C. Bogle (1929–2019), founder and CEO of The Vanguard Group, a pioneer in financial investments John J. Cali (1918–2014), real estate developer Israel Crane (1774–1858), merchant J. Clydesdale Cushman (1887–1955), businessman who co-founded the real estate firm Cushman & Wakefield in 1917 Allen B. DuMont (1901–1965), television pioneer and inventor who created the DuMont Television Network Stephen Glasser (1943–2022), American publisher who founded the Legal Times Floyd Hall (born 1935), CEO of Kmart Charles B. Johnson (born 1933), businessman Ken Kurson (born 1968), political consultant, writer and journalist, who was editor-in-chief of The New York Observer between 2013 and 2017 Geraldine Laybourne (born 1947), former TV executive and entrepreneur, co-founder of Nickelodeon and Oxygen cable networks Benjamin Moore (1905–1917), co-founder with his brother Robert of Benjamin Moore & Co, in Brooklyn in 1883; lived in Upper Montclair Guy T. Viskniskki (1876–1949), newspaper editor and news executive who founded the World War I edition of the Stars and Stripes newspaper while serving as a U.S. Army officer in France with the American Expeditionary Force Bernard Wakefield (c. 1883–1967), British-American executive who co-founded the real estate firm Cushman & Wakefield in 1917
On 18 January, ambassadors from all 27 member states of the EU held an emergency meeting on Trump's threats. After Trump reversed his decision on implementing tariffs, EU officials were sceptical, but announced on 22 January that approval of the trade agreement would resume.
After neutrophils have finished phagocytosing and clearing the antigen at the end of the immune response, they undergo apoptosis, and macrophages are recruited from blood monocytes to help clear apoptotic debris. Macrophages also recruit other immune cells such as monocytes, dendritic cells, natural killer cells, basophils, eosinophils, and T cells through chemokines such as CCL2, CCL4, CCL5, CXCL8, CXCL9, CXCL10, and CXCL11. Along with dendritic cells, macrophages help activate natural killer (NK) cells through secretion of type I interferons (IFN-α and IFN-β) and IL-12. IL-12 acts with IL-18 to stimulate the production of proinflammatory cytokine interferon gamma (IFN-γ) by NK cells, which serves as an important source of IFN-γ before the adaptive immune system is activated. IFN-γ enhances the innate immune response by inducing a more aggressive phenotype in macrophages, allowing macrophages to more efficiently kill pathogens. Some of the T cell chemoattractants secreted by macrophages include CCL5, CXCL9, CXCL10, and CXCL11.
Sources: en.wikipedia.org
Carey (1940), executive officer of the American Association for the Advancement of Science and publisher of Science 1975–1987 Robert Bleiberg (1943), former publisher and managing editor of Barron's Gilman Kraft (1947), former owner and publisher of Playbill Jason Epstein (1949), editorial director of Random House and co-founder of the New York Review of Books Bernard Shir-Cliff (1949), editor of Ballantine Books and Warner Books Arthur Ochs Sulzberger (1951), publisher of The New York Times Lee Guittar (1953), former publisher of the San Francisco Examiner, The Denver Post, Dallas Times Herald, and president of USA Today Richard Goodwin Capen, Jr. (1956), former publisher of the Miami Herald; U.S. ambassador to Spain 1992–1993 Peter Mayer (1956), publisher of Overlook Press and former CEO of Penguin Books Daniel Leab (1957), historian, antiquarian and publisher book catalogues, former editor of Labor History Donald Welsh (1965), founding publisher of outdoors magazine Outside Albert Scardino (1970), publisher of The Georgia Gazette and Pulitzer Prize winner in 1984 Louis Rossetto (1971), founder and publisher of Wired magazine David Rothkopf (1977), CEO and editor of Foreign Policy magazine John R. MacArthur (1978), president and publisher of Harper's magazine, grandson of billionaire John D. MacArthur, benefactor of the MacArthur Fellows Program Jake Dobkin (1998), co-founder and publisher of Gothamist franchise
== Logistics == To meet the testing demand both in terms of turnaround times and specimens processed per day, SHIELD Illinois created an extensive logistics network consisting of The Depot (Chicagoland Central distribution hub), funnel sites (drop points for collection sites located far from The Depot or a central Illinois laboratory), a fleet of 40 vehicles, 12 geographically disparate labs, and a courier network covering 80,000 square miles.
=== Preclinical === Duloxetine oral liquid – serotonin–norepinephrine reuptake inhibitor (SNRI) [16] Generalised anxiety disorder therapeutic - SIMR Biotech – undefined mechanism of action [17] OV-4041 – potassium–chloride cotransporter agonist [18] XYL-3001 (PSYLO-3001) – serotonin 5-HT2A receptor agonist and non-hallucinogenic psychoplastogen [19]
==== Skin depot ==== The absorption of a chemical deposited on skin can also be modeled using first order terms. It is best in that case to separate the skin from the other tissues, to further differentiate exposed skin and non-exposed skin, and differentiate viable skin (dermis and epidermis) from the stratum corneum (the actual skin upper layer exposed). This is the approach taken in [Bois F., Diaz Ochoa J.G. Gajewska M., Kovarich S., Mauch K., Paini A., Péry A., Sala Benito J.V., Teng S., Worth A., in press, Multiscale modelling approaches for assessing cosmetic ingredients safety, Toxicology. doi: 10.1016/j.tox.2016.05.026] Unexposed stratum corneum simply exchanges with the underlying viable skin by diffusion:
Food noise is persistent and intrusive thoughts about food even when food security is not under threat. Although research is still in the early phase, definitions of food noise have emerged, and evidence suggests that food noise is distinct from hunger, food addiction, and food preoccupation. Instead, patients experiencing food noise report constantly ruminating about eating – when to eat, whether they are eating the right types of foods, or whether they are eating the right amount – or having self-recriminating thoughts about their relationship with food. These thoughts have a high cognitive burden and can cause distress, and it has been suggested that food noise may be a reason some people struggle to lose weight. For example, according to WW International, persistent food-related thoughts can make it difficult to adhere to a nutrition or exercise plan and make healthy food choices.
Sources: en.wikipedia.org
== Characterization of inorganic compounds == Because of the diverse range of elements and the correspondingly diverse properties of the resulting derivatives, inorganic chemistry is closely associated with many methods of analysis. Older methods tended to examine bulk properties such as the electrical conductivity of solutions, melting points, solubility, and acidity. With the advent of quantum theory and the corresponding expansion of electronic apparatus, new tools have been introduced to probe the electronic properties of inorganic molecules and solids. Often these measurements provide insights relevant to theoretical models. Commonly encountered techniques are:
Starmer announces the establishment of a "standing army" of specialist police officers to address the violence, and help bring it to an end. The FTSE 100 falls by more than 2%, its biggest drop since January, amid a global market selloff triggered by weaker-than-expected economic data from the US. 6 August 2024 United Kingdom riots: As the rioting enters its seventh day, the number of people arrested in relation to the disorder exceeds 400. The government announces an extra 567 prison places, while police chiefs announce an extra 2,200 riot trained officers will be deployed. Alder Hey Children's Hospital confirms that all the children treated as a result of the Southport stabbing have been discharged. The Senedd is recalled to elect a new First Minister of Wales, with Eluned Morgan nominated as the first woman to hold the post. Thames Water, Yorkshire Water and Northumbrian Water face fines of £168m fines by Ofwat over historic sewage spills. 7 August The Supreme Court rules that Shamima Begum will not be allowed to challenge the removal of her British citizenship. 2024 United Kingdom riots: UK police announce their largest mobilisation since the 2011 England riots, due to the threat of further violence targeting asylum seekers and immigrants, with 6,000 riot police on duty throughout the country and 2,000 in reserve as reinforcements. The first sentences for crimes committed during the riots are handed out to three men who took part in unrest in Southport and Liverpool. The three are sentenced to periods of between 20 months and three years in prison.
=== Organ transplants === Beginning in the 20th century, organ transplants began to take place as scientists knew more about the anatomy of organs. These came later in time as procedures were often dangerous and difficult. Both the source and method of obtaining the organ to transplant are major ethical issues to consider, and because organs as resources for transplant are always more limited than demand for them, various notions of justice, including distributive justice, are developed in the ethical analysis. This situation continues as long as transplantation relies upon organ donors rather than technological innovation, testing, and industrial manufacturing. Animal donor organs and tissue have been subjects of study since the 1960s, and some xenotransplant tissues, particularly heart valves, have been commonly utilized. Xenotransplant has the potential to address the critical shortage in organ grafts. The science behind xenotransplant trials has advanced considerably and more human clinical trials utilizing porcine xenografts are quickly approaching.
The cap of P. semilanceata is 5–25 mm (0.20–0.98 in) in diameter and 6–22 mm (0.24–0.87 in) tall. It varies in shape from sharply conical to bell-shaped, often with a prominent papilla (a nipple-shaped structure), and does not change shape considerably as it ages. The cap margin is initially rolled inward but unrolls to become straight or even curled upwards in maturity. The cap is hygrophanous, meaning it assumes different colors depending on its state of hydration. When it is moist, the cap is ochraceous to pale brown to dark chestnut brown, but darker in the center, often with a greenish-blue tinge. When moist, radial grooves (striations) can be seen on the cap that correspond to the positions of the gills underneath. When the cap is dry, it becomes much paler, a light yellow-brown color. Moist mushrooms have sticky surfaces that result from a thin gelatinous film called a pellicle. This film becomes apparent if a piece of the cap is broken by bending it back and peeling away the piece. When the cap dries from exposure to the sun, the film turns whitish and is no longer peelable. On the underside of the mushroom's cap, there are between 15 and 27 individual narrow gills that are moderately crowded together, and they have a narrowly adnexed to almost free attachment to the stipe. Their color is initially pale brown, but becomes dark gray to purple-brown with a lighter edge as the spores mature. The slender yellowish-brown stipe is 4.5–14 cm (1.8–5.5 in) long by 1–3.5 mm (0.04–0.14 in) thick, and usually slightly thicker towards the base.
== Further reading == Economy, Elizabeth C. (2018). The Third Revolution: Xi Jinping and the New Chinese State. Oxford University Press. ISBN 978-0-19-086607-5. Goodman, David S. G. (2015). Handbook of the Politics of China. Edward Elga. ISBN 978-1-78254-437-1. Li, Cheng (2014a). "Xi Jinping's Inner Circle (Part 2: Friends from Xi's Formative Years)" (PDF). Hoover Institution. Archived (PDF) from the original on 26 September 2020. Retrieved 15 July 2020. Simon, Denis Fred; Cong, Cao (2009). China's Emerging Technological Edge: Assessing the Role of High-End Talent. Cambridge University Press. ISBN 978-0-521-88513-3. Yang, Rufeng (2014). 習近平如何改變中國 [How Xi Jinping is changing China]. China Interpretation Series (in Chinese). Bonfire Limited. p. 12. ISBN 978-986-5721-05-3. Retrieved 23 August 2024. Zhu, Pengpeng (2007). 谜一样的人生 [A Mysterious Life] (in Chinese). Tianma Publishing. ISBN 978-0-9787999-2-2. Retrieved 23 August 2024.
Sources: en.wikipedia.org
NAD+ is a coenzyme found in living cells and is the oxidized form of nicotinamide adenine dinucleotide. It accepts electrons in redox reactions and also serves as a substrate for certain signaling and repair enzymes.
NAD+ becomes NADH when it accepts a hydride ion during oxidation-reduction reactions. NADH then donates electrons to other molecules, after which the carrier can return to the NAD+ form.
No, nicotinamide is a smaller molecule and a component of NAD+. Cells can use nicotinamide to rebuild NAD+ through the salvage pathway.
NAD+ is an oxidized dinucleotide coenzyme that carries electrons in metabolic reactions. It is also consumed by signaling enzymes, including sirtuins and PARPs. Its reduced form is NADH.