The short version of NADH fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-04-20. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical name | Nicotinamide adenine dinucleotide | Oxidized form abbreviated NAD+ |
| Molecular formula | C21H27N7O14P2 | Free acid form |
| Molar mass | 663.43 g/mol | Calculated for free acid |
| CAS Registry Number | 53-84-9 | Common entry for beta-NAD+ |
| Appearance | White to off-white powder | Hygroscopic solid |
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.
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.
== Drug interaction == Pioglitazone/metformin may interact with furosemide, nifedipine, cationic drugs (e.g., amiloride, digoxin, morphine, procainamide, quinidine, quinine, ranitidine, triamterene, trimethoprim, and vancomycin) and certain drugs tend to produce hyperglycemia and may lead to loss of glycemic control (e.g., thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blocking drugs, and isoniazid).
The movement has also recruited and allied with Sunni Muslims; according to researcher Ahmed Nagi, several themes of the Houthi ideology "such as Muslim unity, prophetic lineages, and opposition to corruption [...] allowed the Houthis to mobilize not only northern Zaydis, but also inhabitants of predominantly Shafi'i areas." However, the group is known to have discriminated against Sunni Muslims as well, closing Sunni mosques and primarily placing Zaydis in leadership positions in Houthi-controlled areas. The Houthis lost significant support among Sunni tribes after killing ex-President Saleh. Many Zaydis also oppose the Houthis, regarding them as Iranian proxies and the Houthis' form of Zaydi revivalism as an attempt to "establish Shiite rule in the north of Yemen". In addition, Haykel argued that the Houthis follow "a highly politicised, revolutionary, and intentionally simplistic, even primitivist interpretation of [Zaydism]'s teachings". Their view of Islam is largely based on the teachings of Hussein al-Houthi, collected after his death in a book titled Malazim (Fascicles), a work treated by Houthis as more important than older Zaydi theological traditions, resulting in repeated disputes with established Zaydi religious leaders. The Malazim reflects a number of different religious and ideological influences, including Khomeinism and revolutionary Sunni Islamist movements such as the Muslim Brotherhood.
Laboratory informatics is the specialized application of information technology aimed at optimizing and extending laboratory operations. It encompasses data acquisition (e.g. through sensors and hardware or voice), instrument interfacing, laboratory networking, data processing, specialized data management systems (such as a chromatography data system), a laboratory information management system, scientific data management (including data mining and data warehousing), and knowledge management (including the use of an electronic lab notebook). It has become more prevalent with the rise of other "informatics" disciplines such as bioinformatics, cheminformatics and health informatics. Several graduate programs are focused on some form of laboratory informatics, often with a clinical emphasis. A closely related - some consider subsuming - field is laboratory automation.
Sources: en.wikipedia.org
== Osteogenesis == Bone is formed by one of two processes: endochondral ossification or intramembranous ossification. Endochondral ossification is the process of forming bone from cartilage and this is the usual method. This form of bone development is the more complex form: it follows the formation of a first skeleton of cartilage made by chondrocytes, which is then removed and replaced by bone, made by osteoblasts. Intramembranous ossification is the direct ossification of mesenchyme as happens during the formation of the membrane bones of the skull and others. During osteoblast differentiation, the developing progenitor cells express the regulatory transcription factor Cbfa1/Runx2. A second required transcription factor is Sp7 transcription factor. Osteochondroprogenitor cells differentiate under the influence of growth factors, although isolated mesenchymal stem cells in tissue culture may also form osteoblasts under permissive conditions that include vitamin C and substrates for alkaline phosphatase, a key enzyme that provides high concentrations of phosphate at the mineral deposition site. In turn osteoblasts may give rise to osteocytes in a process dependent on the vascular musculature of blood vessels in the bone.
Analysis of the debris at the test site of the United States' first thermonuclear weapon, Ivy Mike (1 November 1952, Enewetak Atoll), besides einsteinium, fermium, plutonium and americium also revealed isotopes of berkelium, californium and curium, in particular 245Cm, 246Cm and smaller quantities of 247Cm, 248Cm and 249Cm. Atmospheric curium compounds are poorly soluble in common solvents and mostly adhere to soil particles. Soil analysis revealed about 4,000 times higher concentration of curium at the sandy soil particles than in water present in the soil pores. An even higher ratio of about 18,000 was measured in loam soils. The transuranic elements up to fermium, including curium, should have been present in the natural nuclear fission reactor at Oklo, but any quantities produced then would have long since decayed away.
Members of some Christian sects in the Southern United States are regularly bitten while participating in "snake handling" rituals. Snake handling is when people hold venomous snakes, unprotected, as part of a religious service inspired by a literal interpretation of the Bible verses Mark 16:17–18, which reads, "In my name ... They shall take up serpents ...."
Sources: en.wikipedia.org
Pressed and dried: Vascular plant (flowering plants, conifers, ferns) specimens are pressed and dried plants that are mounted on herbarium sheets. Various techniques are used to attach the plants with the most common method of using archival adhesive with heavier portions of the plant supported additionally by linen thread or narrow strips of gum-backed linen tape or polyester film. Specimens are best pressed with moderate pressure, permitting as much air circulation as possible. This is commonly achieved by strapping sheets in a press made of heavy cardboard or plywood. If there are loose seeds or fruits, these are placed in a small fragment packet, which also is glued to the sheet. A label with collection information is glued on the bottom right corner. Dried: Small bryophytes (mosses, hepatics or liverworts, and hornworts) are dried and placed loosely in folded packets. The label is glued on the front of the packet and the packets are filed loosely in boxes, glued to sheets of mounting paper, or placed loosely in folders. Stored in fluid: Preserved material can be kept in a glass jar filled with preservative fluid. By storing this way, the botanical specimens are maintained in a usable condition by inhibiting enzymatic and microbial attack. This method can be used where drying, pressing and mounting on a herbarium sheet is unsuitable. This method allows for a better three-dimensional arrangement of flower parts or fruits for storage.
When initially discovered, some scientists proposed that Osedax was a whale-bone specialist, a notion later disproven by the discovery of Osedax on a variety of skeletal substrates including bone fragments, teleost bones, shark teeth, reptile and bird skeletons, pinniped bones, experimentally placed cow bones, and even human remains. Multiple species of Osedax can co-exist in close proximity, even on the same bone. Osedax and their borings enhance local biodiversity by dissolving the tough external cortical bone and tunneling through their internal layers, increasing structural complexity and providing new regions for microfauna to colonize. As such, Osedax are considered ecosystem engineers. However, these borings compromise the structural integrity of the bones, causing them to collapse after extensive boring, rendering these new habitats temporary. The role of Osedax in the degradation of marine vertebrate remains is important to marine vertebrate taphonomy.
Four of the six coordination sites are provided by the corrin ring and a fifth by a dimethylbenzimidazole group. The sixth coordination site, the reactive center, is variable, being a cyano group (–CN), a hydroxyl group (–OH), a methyl group (–CH3) or a 5′-deoxyadenosyl group. Historically, the covalent carbon–cobalt bond is one of the first examples of carbon-metal bonds to be discovered in biology. The hydrogenases and, by necessity, enzymes associated with cobalt utilization, involve metal-carbon bonds. Animals can convert cyanocobalamin and hydroxocobalamin to the bioactive forms adenosylcobalamin and methylcobalamin by enzymatically replacing the cyano or hydroxyl groups.
Sources: en.wikipedia.org
NAD+ is the oxidized form, while NADH is the reduced form carrying an additional hydride equivalent. The pair participates in reversible electron transfer reactions. Their ratio helps indicate the redox state of a compartment.
NAD+ itself is not classified as a vitamin, but its precursor niacin is an essential nutrient in humans. Cells synthesize NAD+ from niacin, nicotinamide, nicotinamide riboside, or tryptophan. The intact dinucleotide is not obtained directly from typical diets in meaningful amounts.
Age-related studies often examine whether NAD+ levels decline in tissues and whether that decline affects mitochondrial function or DNA repair. Interventions using precursor molecules raise open questions about cause and effect. Current evidence does not establish that changing NAD+ levels slows human aging.
Common laboratory methods include enzymatic cycling, high-performance liquid chromatography, and liquid chromatography with mass spectrometry. The choice depends on sample type, expected concentration, and available equipment.