A practical reference on NADH: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-11-15 and is reviewed periodically as new material appears.
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.
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.
Beyond redox catalysis, NAD+ is a substrate for enzymes that transfer ADP-ribose or remove acetyl groups from proteins. Sirtuins and poly(ADP-ribose) polymerases consume NAD+ and release nicotinamide as a byproduct. These reactions connect cellular energy status to gene regulation, DNA repair, and stress responses. Because NAD+ is used rather than merely recycled in such signaling, its concentration reflects both biosynthesis and consumption. The balance between salvage and de novo synthesis pathways determines available pools in different tissues.
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.
| 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. |
Laboratory measurement of NAD+ usually begins with rapid sample quenching because the molecule can change form after collection. Enzymatic cycling assays amplify signal through coupled reactions and are suited to small samples. High-performance liquid chromatography with ultraviolet detection separates NAD+ from related nucleotides. Liquid chromatography-mass spectrometry offers higher specificity and can distinguish NAD+ from close analogs. Each method has trade-offs in sensitivity, throughput, and equipment needs, so reported values depend heavily on extraction and detection choices.
Stability of NAD+ depends on form, temperature, pH, and water content. The solid is generally more stable than solutions, and it should be kept dry and cold. In solution, hydrolysis can cleave the dinucleotide, especially under alkaline conditions or at elevated temperature. Light exposure may also contribute to degradation. Buffers, chelating agents, and sterile handling can reduce losses, but no single condition preserves all preparations indefinitely. Researchers often prepare working solutions shortly before use and verify activity or purity after storage.
Quality control for NAD+ relies on identity, purity, and functional tests. A certificate of analysis may report high-performance liquid chromatography purity, ultraviolet spectrum, water content, and residual solvents. Because NAD+ is hygroscopic, gravimetric values can shift as material absorbs water, so purity should be interpreted alongside storage history. Mass spectrometry confirms molecular identity, while enzymatic assays show whether the material supports dehydrogenase activity. Commercial material is available as the free acid and as salts, and the counterion affects molecular weight, solubility, and how concentrations are calculated.
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.
Živojinović (nicknamed Bata) was born in the village of Koraćica under the Kosmaj mountain near Mladenovac, at the time Kingdom of Yugoslavia (now Serbia). His father, Dragoljub, was an official and his mother Tiosava was a housewife. He had two sisters, Stanka and Nada, and grew up in a patriarchal household. A conflict between Dragoljub and the Chetniks during World War II forced the family to move to Belgrade. The family lived in Crveni Krst. Young Bata often went with his friends to the cinema, which sparked his interest in acting. Loitering around the "20th October" cinema, he watched AKUD Branko Krsmanović, a Belgrade troupe, through the window for several days until he was welcomed inside. There he befriended Soja Jovanović, instrumental in the developing of Bata's love for acting, Rade Marković, Olivera Marković, Mića Tomić, and Bata Paskaljević. After graduating from acting schools in Niš and Novi Sad, he enrolled at the Drama Academy in Belgrade.
A 15-hydroxyicosatetraenoate dehydrogenase metabolizes 15-hydroxyicosatetraenoic acid (i.e. 15(S)-hydroxy-5Z,8Z,11Z,13E-eicosatetraenoic acid or 15-HETE) to its 15-keto analog, 15-oxo-ETE, using NAD+ and NADH rather than NADP+ and NADPH as its co-factors. 15-Oxo-ETE appears to have a somewhat different spectrum of activities than its precursor, 15-HETE (see 15-Hydroxyicosatetraenoic acid
CYB5R1, NADH-cytochrome b5 reductase 1, located on chromosome 1q32.1 with 9 exons that encode for c5br. CYB5R2, NADH-cytochrome b5 reductase 2, located on chromosome 11p15.4 with 12 exons that encode for c5br. CYB5R3, NADH-cytochrome b5 reductase 3, located on chromosome 22q13.2 with 12 exons that encode for c5br. CYB5R4, NADH-cytochrome b5 reductase 4, located on chromosome 6q14.2 with 16 exons that encode for c5br. Mutations in cytochrome b5 reductase can lead to many disorders, including autosomal recessive congenital methemoglobinemia. There are over 65 mutations of the enzyme that can lead to various types of the disorder. Some include:
Sources: en.wikipedia.org
March 12 – 17: 2018 Youth Pan American Championships (Men) in Guadalajara In the final, Argentina defeated Mexico, 3–2. Canada took third place and Paraguay took fourth place. March 12 – 17: 2018 Youth Pan American Championships (Women) in Guadalajara In the final, Argentina defeated Uruguay, 4–0. Mexico took third place and Paraguay took fourth place. May 13 – 20: 2018 Asian Women's Hockey Champions Trophy in Donghae City South Korea defeated India, 1–0, to win their third Asian Women's Hockey Champions Trophy title. China took third place. October 18 – 28: 2018 Asian Men's Hockey Champions Trophy in Muscat Note: Due to heavy rain, both India and Pakistan took first place here. Malaysia took third place. July 11 – 15: IFA 2018 Fistball U18 World Championships in Roxbury Township July 24 – 28: IFA 2018 Fistball Women's World Championship in Linz
National teams April 29 – May 1: 2018 FIBA 3x3 Asia Cup in Shenzhen Men: Australia defeated Mongolia, 17–16, in the final. Japan took third place. Women: New Zealand defeated China, 14–11, in the final. Australia took third place. August 5 – 11: 2018 FIBA Under-18 Asian Championship in Thailand In the final, Australia defeated New Zealand, 73–62, to win their 1st title. China took third place. Note: All teams mentioned here, plus Philippines, have qualified to compete at the 2019 FIBA Under-19 Basketball World Cup. October 28 – November 3: 2018 FIBA Under-18 Women's Asian Championship in Bangalore China defeated Japan, 89–76, to win their fifth consecutive and 16th overall FIBA Under-18 Women's Asian Championship title. Australia took third place. Note: All teams mentioned here, plus South Korea, have qualified to compete at the 2019 FIBA Under-19 Women's Basketball World Cup. Clubs teams November 17, 2017 – May 2: 2017–18 ABL season San Miguel Alab Pilipinas defeated Mono Vampire, 3–2 in games played in a 5-legged final, to win their first ABL title. July 17 – 22: Summer Super 8 in Macau Guangzhou Long-Lions defeated Seoul Samsung Thunders, 78–72, to win their first title. Incheon Electroland Elephants took third place.
Fatty change, or steatosis, is the accumulation of fatty acids in liver cells. This can be seen as fatty globules under the microscope. Alcoholism causes development of large fatty globules (macro-vesicular steatosis) throughout the liver and can begin to occur after a few days of heavy drinking. Alcohol is metabolized by alcohol dehydrogenase (ADH) into acetaldehyde, then further metabolized by aldehyde dehydrogenase (ALDH) into acetic acid, which is finally oxidized into carbon dioxide (CO2) and water (H2O). This process generates NADH, and increases the NADH/NAD+ ratio. A higher NADH concentration induces fatty acid synthesis while a decreased NAD level results in decreased fatty acid oxidation. Subsequently, the higher levels of fatty acids signal the liver cells to compound it to glycerol to form triglycerides. These triglycerides accumulate, resulting in fatty liver.
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 the oxidized form and NADH is the reduced form of the same coenzyme. NAD+ accepts electrons during oxidation reactions, becoming NADH, which can donate electrons in other reactions. The ratio between them helps describe a cell's redox state.