If you have been reading about NADH and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-03-24. Numbers and descriptions here follow the published literature rather than marketing material.
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.
The stability of NAD+ depends on pH, temperature, light exposure, and the presence of degradative enzymes. Aqueous solutions are generally more stable under mildly acidic to neutral conditions and degrade faster under alkaline conditions or prolonged heat. The solid is hygroscopic and should be stored desiccated, often frozen, and protected from repeated freeze-thaw cycles. In laboratory handling, aliquots reduce repeated temperature changes, and chelating agents may limit metal-catalyzed hydrolysis in some buffers. These practices matter because even small amounts of NADH or hydrolysis products can interfere with quantitative assays.
Quality control for NAD+ materials typically combines identity, purity, and water content checks. Identity may be confirmed by ultraviolet spectrum, retention time in chromatography, or mass accuracy, while purity is assessed by HPLC peak area or quantitative nuclear magnetic resonance. Residual water and solvents can affect molar calculations and enzyme assays, so Karl Fischer titration or thermogravimetric analysis may be used. Commercial materials vary in grade and counterion form, and published methods should specify the exact salt or hydrate when reporting concentrations. Regulatory status depends on intended use, with research reagents, dietary ingredients, and clinical products treated under different frameworks.
Quantification of NAD+ in biological samples usually relies on separation techniques coupled to sensitive detection. High-performance liquid chromatography with ultraviolet detection can measure the oxidized form by its absorbance near 260 nm, while mass spectrometry provides greater specificity and can distinguish NAD+ from close analogs. Enzymatic cycling assays use coupled dehydrogenase reactions to amplify signal and estimate NAD+ concentrations in cell or tissue extracts. Because NAD+ and NADH interconvert rapidly, sample preparation must quench metabolism quickly and preserve the redox state before analysis.
| 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. |
NAD+ is a dinucleotide composed of adenine, ribose, and nicotinamide moieties linked by phosphate groups. Its oxidized form carries a positive charge on the nicotinamide ring, which enables reversible hydride transfer. The molecule functions as a coenzyme in oxidoreductase reactions rather than as a dietary vitamin in its intact form. Cells maintain separate pools in cytoplasm, mitochondria, and nucleus. This compartmentalization allows distinct redox environments while preserving a shared chemical identity.
In glycolysis, NAD+ accepts electrons during the oxidation of glyceraldehyde-3-phosphate, forming NADH. The tricarboxylic acid cycle and fatty acid oxidation also generate NADH, which donates electrons to the mitochondrial electron transport chain. This flow supports ATP synthesis and helps maintain the redox balance of the cell. Other dehydrogenases use NAD+ as a cofactor for biosynthetic reductions and detoxification reactions. NADH is later reoxidized to sustain continued flux through these pathways.
Beyond electron transfer, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer ADP-ribose units. Sirtuins, poly(ADP-ribose) polymerases, and CD38 consume NAD+ in regulatory reactions. These activities link NAD+ availability to DNA repair, chromatin modification, calcium signaling, and metabolic stress responses. Because consumption can exceed biosynthesis under some conditions, cellular NAD+ levels are dynamic rather than fixed. Enzyme affinity and local synthesis also influence how much NAD+ is available for signaling.
NAD+ is the oxidized form of nicotinamide adenine dinucleotide, a coenzyme built from two nucleotides joined by a phosphate linkage. One nucleotide carries adenine, and the other carries nicotinamide; the plus sign denotes a formal positive charge on the nicotinamide ring, not a free proton. In cells, NAD+ and its reduced partner NADH form a reversible redox pair. That pair participates in electron transfer reactions throughout metabolism. The abbreviation NAD+ is common in biochemistry, while NAD(H) sometimes denotes the combined pool.
The molecule was first described in the early twentieth century as a factor that promoted fermentation in yeast extracts. Later work linked it to hydrogen transfer and to the oxidation of nutrients in living tissues. Its structure was resolved as a dinucleotide, which explained why it could accept and donate electrons at specific enzyme sites. Today, NAD+ is recognized as a central substrate and signaling precursor, not merely a metabolic cofactor. Whether all observed NAD+ changes reflect causal signaling remains an open question.
Related compounds include NADH, the reduced form, and NADP+, which carries an additional phosphate group. NADP+ and NADPH often serve in biosynthetic and antioxidant reactions, while NAD+ and NADH are more associated with energy-yielding catabolism. Nicotinamide, nicotinic acid, and nicotinamide riboside are precursors that can enter salvage pathways. The exact contribution of dietary precursors to tissue NAD+ pools is an area of active investigation. Some studies measure labeled precursors to trace those routes.
Tea bricks or compressed tea are produced for convenience in transport, storage, and ageing. It can usually be stored longer without spoilage than loose leaf tea. Compressed tea is prepared by loosening leaves from the cake using a small knife, and steeping the extracted pieces in water. During the Tang dynasty, as described by Lu Yu, compressed tea was ground into a powder, combined with hot water, and ladled into bowls, resulting in a "frothy" mixture. In the Song dynasty, the tea powder would instead be whisked with hot water in the bowl. Although no longer practiced in China today, the whisking method of preparing powdered tea was transmitted to Japan by Zen Buddhist monks, and is still used to prepare matcha in the Japanese tea ceremony. Chinese pu-erh is often distributed in the form, as other teas may sometimes be. Compressed tea was the most common form of tea in China during the Tang dynasty. By the beginning of the Ming dynasty, it had been displaced by loose-leaf tea. In Mongolia, tea bricks were ubiquitous enough to be used as a form of currency. Among Himalayan peoples, compressed tea is consumed by combining it with yak butter and salt to produce butter tea.
== History == Lime sulfur is believed to be the earliest synthetic chemical used as a pesticide, having been used in France in the 1840s in order to control grapevine powdery mildew, Uncinula necator, which was introduced from the United States in 1845 and reduced wine production by 80%. In 1886, it was first used in California to control San Jose scale. Beginning around 1904, commercial suppliers began to manufacture lime sulfur; prior to that time, gardeners were expected to manufacture their own. By the 1920s, essentially all commercial orchards in Western countries were protected by regular spraying with lime sulfur. However, by the 1940s, lime sulfur began to be replaced by synthetic organic fungicides that posed less risk of damage to the crop's foliage.
==== Elimination ==== Mescaline given orally is excreted 87% in urine within 24 hours and 92% in urine within 48 hours. During the first hour after administration, 81.4% of mescaline is excreted unchanged while 13.2% is excreted as its deaminated metabolite 3,4,5-trimethoxyphenylacetic acid (TMPAA). However, after the first hour, the percentage excreted as unchanged mescaline declines and the percentage excreted as TMPAA rises. Ultimately, mescaline is excreted in urine 28 to 60% unchanged, 27 to 30% or more as TMPAA, 5% as N-acetyl-3,4-dimethoxy-5-hydroxyphenylethylamine, and less than 0.1% as N-acetylmescaline. Other minor or trace excreted metabolites have also been observed. In a more modern study published in 2025, mescaline was eliminated in urine 53% as unchanged mescaline and 31% as TMPAA. Mescaline was originally reported to have an elimination half-life of 6 hours based on a study conducted in the 1960s. However, subsequent research published in the 2020s found that its half-life is actually about 3.6 hours (range 2.6–5.3 hours). The previous higher estimate is believed to have been due to small sample numbers and collective measurement of mescaline metabolites. The elimination half-life of mescaline does not appear to be dose-dependent. TMPAA has a half-life of about 3.7 to 4.1 hours, similar to that of mescaline. Mescaline has a similar half-life as LSD yet has a longer duration. This is due to mescaline having slower absorption and onset rather than a longer half-life.
An additional 35 primordial nuclides (to a total of 286 primordial nuclides), are radioactive with known half-lives, but have half-lives longer than 100 million years, allowing them to exist from the beginning of the Solar System. See list of nuclides for details. All the known stable nuclides occur naturally on Earth; the other naturally occurring nuclides are radioactive but occur on Earth due to their relatively long half-lives, or else due to other means of ongoing natural production. These include the afore-mentioned cosmogenic nuclides, the nucleogenic nuclides, and any radiogenic nuclides formed by ongoing decay of a primordial radioactive nuclide, such as radon and radium from uranium. An additional ~3000 radioactive nuclides not found in nature have been created in nuclear reactors and in particle accelerators. Many short-lived nuclides not found naturally on Earth have also been observed by spectroscopic analysis, being naturally created in stars or supernovae. An example is aluminium-26, which is not naturally found on Earth but is found in abundance on an astronomical scale. The tabulated atomic masses of elements are averages that account for the presence of multiple isotopes with different masses. Before the discovery of isotopes, empirically determined noninteger values of relative atomic mass confounded scientists. For example, a sample of chlorine contains 75.8% chlorine-35 and 24.2% chlorine-37, giving an average atomic mass of 35.5 daltons.
Sources: en.wikipedia.org
== Following artwork == In 2008, Evaristti announced that he and musician Kenneth Thordal were planning another artwork involving goldfish, called FIVE2TWELVE. At this exhibition, the body of American death row inmate Gene Hathorn Jr. would be turned into freeze-dried fish food and placed in front of a pool of goldfish, and the audience would have to choose between feeding the fish with freeze-dried human meat and letting them starve to death. The plans were abandoned the following year, when Hathorn's sentence was commuted to three concurrent life sentences.
The Jameson Raid (Afrikaans: Jameson-inval, lit. ''Jameson's Invasion'', 29 December 1895 – 2 January 1896) was a botched raid against the South African Republic (commonly known as the Transvaal) carried out by British colonial administrator Leander Starr Jameson, under the employment of Cecil Rhodes. It involved 500 British South Africa Company police and was launched from Rhodesia over the New Year weekend of 1895–96. Paul Kruger, for whom Rhodes had great personal hatred, was president of the South African Republic at the time. The raid was intended to trigger an uprising by the primarily British expatriate and settler workers (known as Uitlanders) in the Transvaal, but it failed. The workers were referred to as the Johannesburg Conspirators. They were expected to recruit an army and prepare for an insurrection; however, the raid was ineffective, and no uprising took place. The results included embarrassment of the British government; the replacement of Cecil Rhodes as prime minister of the Cape Colony; and the strengthening of Boer dominance of the Transvaal and its gold mines. Also, the withdrawal of so many fighting men left Rhodesia vulnerable, one factor that led just a couple of months later to the Second Matabele War. The raid was a contributory cause of the Second Boer War.
positional cloning Also map-based cloning. A strategy for identifying and cloning a candidate gene based on knowledge of its locus or position alone and with little or no information about its products or function, in contrast to functional cloning. This method usually begins by comparing the genomes of individuals expressing a phenotype of unknown provenance (often a hereditary disease) and identifying genetic markers shared between them. Regions defined by markers flanking one or more genes of interest are cloned, and the genes located between the markers can then be identified by any of a variety of means, e.g. by sequencing the region and looking for open reading frames, by comparing the sequence and expression patterns of the region in mutant and wild-type individuals, or by testing the ability of the putative gene to rescue a mutant phenotype.
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.
Common methods include LC-MS, HPLC with UV detection, and enzymatic cycling assays. Rapid quenching is needed because NAD+ and NADH interconvert. The chosen method should be validated for the sample matrix.