A practical reference on Dinucleotide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-19 and is reviewed periodically as new material appears.
NAD+ is a dinucleotide composed of two nucleotides joined by a pyrophosphate linkage. One nucleotide contains adenine, and the other contains nicotinamide. The oxidized form carries a positive charge on the nicotinamide ring and is abbreviated NAD+. It functions as a cofactor in hydride-transfer reactions, accepting electrons in catabolic pathways. In cells, it interconverts with reduced NADH, forming a redox couple central to energy metabolism. The molecule is water-soluble and does not cross cell membranes freely without specific transport or precursor pathways.
The nicotinamide ring undergoes reversible reduction at the para position, converting NAD+ to NADH. This reaction transfers a hydride equivalent, not a free hydrogen atom or electron alone. Because the redox pair has a defined reduction potential, it links oxidation of fuels to respiratory chain activity. Many dehydrogenases use NAD+ as a co-substrate and produce NADH. The ratio of NAD+ to NADH reflects metabolic state and influences flux through several pathways.
Beyond redox chemistry, NAD+ serves as a substrate for enzymes that transfer ADP-ribose or remove acetyl groups. Sirtuins, PARPs, and CD38-family enzymes consume NAD+ and produce nicotinamide and ADP-ribose-related products. These reactions link NAD+ availability to DNA repair, chromatin modification, and cellular signaling. Because the molecule is central to energy metabolism and regulation, changes in its concentration are studied in aging, immunity, and metabolic research. The balance between synthesis and consumption varies by tissue, developmental stage, and physiological state.
In humans, NAD+ can be synthesized from nicotinic acid, nicotinamide, nicotinamide riboside, and tryptophan through overlapping pathways. The salvage pathway recycles nicotinamide back to NAD+ and is often considered a major route in many tissues. Dietary precursors and intracellular recycling both contribute to the pool, but the quantitative importance of each source remains an active research question. NAD+ levels are not uniform across organs or cell compartments. Measurements in blood do not necessarily reflect concentrations inside tissues.
| Property | Value | Notes |
|---|---|---|
| IUPAC name | Nicotinamide adenine dinucleotide | Oxidized dinucleotide form |
| CAS Registry Number | 53-84-9 | Common entry for beta-NAD+ |
| Molecular formula | C21H27N7O14P2 | Free acid form |
| Molar mass | 663.43 g/mol | Calculated for free acid |
| Water solubility | Freely soluble | Charged dinucleotide; less soluble in organic solvents |
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.
Nicotinamide adenine dinucleotide, commonly abbreviated NAD+, is a dinucleotide coenzyme built from an adenine nucleotide and a nicotinamide nucleotide joined by a pyrophosphate linkage. Its oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, carries a hydride equivalent. The molecule participates in hundreds of oxidoreductase reactions, where it accepts or donates electrons and protons. Because it can cycle between oxidized and reduced states without net consumption, NAD+ functions as a reusable electron carrier rather than a fuel molecule.
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.
== Bibliography == Cowie, J. M. G. (John McKenzie Grant) (1991). Polymers: chemistry and physics of modern materials. Glasgow: Blackie. ISBN 978-0-412-03121-2. Hall, Christopher (1989). Polymer materials (PDF) (2nd ed.). London; New York: Macmillan. ISBN 978-0-333-46379-6. Rudin, Alfred (1982). The elements of polymer science and engineering. Academic Press. ISBN 978-0-12-601680-2. Wright, David C. (2001). Environmental Stress Cracking of Plastics. RAPRA. ISBN 978-1-85957-064-7.
=== Salt coagulants === Calcium sulfate (gypsum) (Chinese: 石膏; pinyin: shígāo) is the traditional and most widely used coagulant to produce Chinese-style tofu, it produces a tofu that is tender but slightly brittle in texture. The coagulant itself has very little noticeable taste. Also known as gypsum, calcium sulfate is quarried from geological deposits, and no chemical processing or refining is needed, making it the cheapest coagulant used in tofu production. When used in production, the coagulation reaction is slower due to its low solubility, forming a smooth, more gelatinous tofu with relatively high water content and soft texture. Chloride-type nigari salts or lushui (simplified Chinese: 卤水; traditional Chinese: 鹵水; pinyin: lǔshuǐ) may also be used. Magnesium chloride and calcium chloride are highly soluble in water and affect soy protein in the same way, whereas gypsum is only very slightly soluble in water and acts differently in soy protein precipitation, the basis of tofu formation. These are the coagulants used to make tofu with a smooth and tender texture. In Japan, a white powder called nigari, which consists primarily of magnesium chloride, is produced from seawater after the sodium chloride is removed and the water evaporated. Depending on its production method, nigari/lushui may also contain small quantities of magnesium sulfate (Epsom salt), potassium chloride, calcium chloride, and trace amounts of other naturally occurring salts.
== June 4, 1915 (Friday) == Third Battle of Krithia — British, French, and Indian forces made a third and last attempt to capture Achi Baba, the main position for Ottoman defenses on the Gallipoli peninsula but were beaten back, sustaining some 6,500 casualties. Ottoman casualties were higher, ranging between 9,000 and 10,000 men. The LZ 40, the first Zeppelin P Class airship of the Imperial German Navy, was flown to bomb targets in London. The Royal Norwegian Navy Air Service test flew the M.F.1 floatplane in Horten, Norway, the first Marinens Flyvebaatfabrikk model based on a design by Maurice Farman. The fraternity Alpha Sigma Nu was founded at Marquette University as an honor society for Jesuit colleges. Born: Modibo Keïta, Malian statesman, first President of Mali; in Bamako Coura, French Sudan (present-day Bamako, Mali) (d. 1977) Walter Hadlee, New Zealand cricketer, batman for the New Zealand national cricket team from 1937 to 1951; in Lincoln, New Zealand (d. 2006)
=== Self-efficacy === Self-efficacy refers to a belief that one's ability to accomplish a task is a function of personal effort. Low self-efficacy, or a disconnect between ability and personal effort, is associated with depression; by comparison, high self-efficacy is associated with positive change, including overcoming abuse, overcoming eating disorders, and maintaining a healthy lifestyle. High self-efficacy also has positive benefits for one's immune system, aids in stress management, and decreases pain. A related concept, Personal effectiveness, is primarily concerned with planning and the implementation of methods of accomplishment.
Sources: en.wikipedia.org
In 1977, Sanger then adopted a primer-extension strategy to develop more rapid DNA sequencing methods at the MRC Centre, Cambridge, UK. This technique was similar to his "Plus and Minus" strategy, however, it was based upon the selective incorporation of chain-terminating dideoxynucleotides (ddNTPs) by DNA polymerase during in vitro DNA replication. Sanger published this method in the same year. Gilbert's interest in DNA sequencing arose from studies of gene regulation, particularly the lac operon. The method represented one of the first practical techniques for rapid DNA sequencing and earned Gilbert and Frederick Sanger the 1980 Nobel Prize in Chemistry for their independent contributions to nucleic acid sequencing.
=== Triacidic bases === When one molecule of base via complete ionization produces three hydroxide ions, the base is said to be triacidic or triprotic. Examples of triacidic bases are: Aluminium hydroxide, ferric hydroxide, gold(III) hydroxide.
== Thenford gardens and arboretum == The Heseltines purchased Thenford House and its grounds in 1976. The house was bought privately with the aid of a large loan, and they are thought to have paid around £750,000 (approximately £7.58m at 2025, RPI prices), and to have spent a similar sum on renovating the property. They also own a number of farms in the area. Over the next 25 years they restored 40 acres (16 ha) of woodland together with the walled garden, medieval fish-ponds, and a 2 acres (0.81 ha) lake. There is also a sculpture garden, which includes a large bronze bust of Lenin, from Latvia. At the turn of the century they decided to create various ornamental features in the garden and increase the range of trees and shrubs in the arboretum. Covering over 70 acres (28 ha) the arboretum is stocked with over 3,000 different species. Their arboretum was featured in a one-off documentary on BBC Two in December 2005. In October 2016 the Heseltines were featured on BBC's Gardeners' World, discussing their garden at Thenford House, parts of which were modelled after the gardens at Château de Villandry. The garden is open to the public by appointment only.
Sources: en.wikipedia.org
=== Mitochondrial function and morphology === Prohibitins are assembled into a ring-like structure with 16–20 alternating Phb1 and Phb2 subunits in the inner mitochondrial membrane. The precise molecular function of the PHB complex is not clear, but a role as chaperone for respiratory chain proteins or as a general structuring scaffold required for optimal mitochondrial morphology and function are suspected. Recently, prohibitins have been demonstrated to be positive, rather than negative, regulators of cell proliferation in both plants and mice.
Traditionally, homeless shelters ban alcohol. In 1997, as the result of an inquest into the deaths of two people experiencing homelessness who recreationally used alcohol two years earlier, Toronto's Seaton House became the first homeless shelter in Canada to operate a "wet shelter" on a "managed alcohol" principle in which clients are served a glass of wine once an hour unless staff determine that they are too inebriated to continue. Previously, people experiencing homelessness who consumed excessive amounts of alcohol opted to stay on the streets, often seeking alcohol from unsafe sources such as mouthwash, rubbing alcohol or industrial products which, in turn, resulted in frequent use of emergency medical facilities. The programme has been duplicated in other Canadian cities, and a study of Ottawa's "wet shelter" found that emergency room visit and police encounters by clients were cut by half. The study, published in the Canadian Medical Association Journal in 2006, found that serving people experiencing long-term homelessness and who consume excessive amounts of alcohol controlled doses of alcohol also reduced their overall alcohol consumption. Researchers found that programme participants cut their alcohol use from an average of 46 drinks a day when they entered the programme to an average of 8 drinks and that their visits to emergency rooms dropped from 13.5 to an average of 8 per month, while encounters with the police fall from 18.1 to an average of 8.8.
An opinion issued by the European Commission's Scientific Committee on Consumer Safety, concluding spray tanning with DHA did not pose risk, has been heavily criticized by specialists. This is because the cosmetics industry in Europe chose the evidence to review, according to the commission itself. Thus, nearly every report the commission's eventual opinion referenced came from studies that were never published or peer-reviewed and, in the majority of cases, were performed by companies or industry groups linked to the manufacturing of DHA. The industry left out nearly all of the peer-reviewed studies published in publicly available scientific journals that identified DHA as a potential mutagen. A study by scientists from the Department of Dermatology, Bispebjerg Hospital, published in Mutation Research has concluded DHA 'induces DNA damage, cell-cycle block and apoptosis' in cultured cells.
Sources: en.wikipedia.org
NAD+ is the oxidized form, while NADH is the reduced form carrying an added hydride. The two form a redox pair that cells use in many energy-yielding reactions.
NAD+ is a small organic cofactor, not a protein or enzyme. It binds temporarily to enzymes such as dehydrogenases to assist electron transfer.
Intact NAD+ is generally not taken up efficiently by most cells because it is charged and water-soluble. Cells often rely on precursors such as nicotinamide or nicotinamide riboside to produce NAD+ internally.
The plus sign indicates the oxidized form of nicotinamide adenine dinucleotide, which can accept electrons. When it accepts electrons, it becomes NADH. The two forms together support redox reactions in cells.