If you have been reading about HPLC 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 2025-10-04. Numbers and descriptions here follow the published literature rather than marketing material.
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 commonly measured by high-performance liquid chromatography with ultraviolet detection, often at 254 or 260 nm. Enzymatic cycling assays provide higher sensitivity by coupling NAD+ to a reporter reaction. Mass spectrometry can distinguish NAD+ from close analogues and confirm isotope labeling. Sample preparation usually involves rapid quenching of metabolism to prevent interconversion with NADH. Because NAD+ and NADH differ by one hydride, extraction conditions strongly affect the measured ratio.
In aqueous solution, NAD+ is most stable under mildly acidic to neutral conditions and degrades faster at high pH or elevated temperature. The molecule can hydrolyze at the pyrophosphate bond or undergo nonenzymatic cyclization. Buffers, chelating agents, and cold temperatures slow these losses during analysis. Repeated freeze-thaw cycles are generally avoided because they can promote degradation and concentration changes. Light exposure is also controlled, though NAD+ is less photolabile than some related nucleotides.
| Property | Value | Notes |
|---|---|---|
| CAS number | 53-84-9 | Refers to the free acid form of NAD+. |
| Molecular formula | C21H27N7O14P2 | Free acid; salts include additional counterions. |
| UV absorbance maximum | 259-260 nm | Used for detection and concentration estimation. |
| Typical storage | -20 °C or below, desiccated | Protect from light and moisture; avoid repeated freeze-thaw. |
| Common analytical method | HPLC-UV or LC-MS | Enzymatic cycling is an alternative for low-abundance samples. |
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.
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.
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.
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.
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.
This tornado was part of a small outbreak that affected Europe that day, which produced a total of seven tornadoes. In Poland, one person was injured by an F2 tornado that impacted the towns of Librantowa and Koniuszowa, damaging numerous structures, 15 of which had their roofs torn off. Numerous reports of damaging straight-line winds and large, destructive hail were received as well. Weather of 2021 List of tornadoes rated on the International Fujita scale List of European tornadoes and tornado outbreaks List of F4 and EF4 tornadoes List of F4 and EF4 tornadoes (2020–present) October 2022 European tornado outbreak – An EF3 tornado struck Bihucourt F4 Tornado Hits Hodonín, Czechia - Jun. 24, 2021 tornádo v Hodoníně F4 Tornado Hits Hodonín, Czechia - Jun. 24, 2021 tornádo v Hodoníně (Part 2) Inside of an F4 tornado (full version)
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
Sources: en.wikipedia.org
July 28 – August 4: 2018 Senior League Baseball World Series in Easley at Easley Recreation Complex The Pariba Little League (Caribbean) defeated the Naamans Little League (East), 7–2, in the final. July 29 – August 5: 2018 Little League Intermediate (50/70) Baseball World Series in Livermore at Max Baer Park The West Seoul LL (Asia-Pacific) defeated the Livermore/Granada LL (Host), 10–0, in the final. August 12 – 19: 2018 Junior League World Series in Taylor at Heritage Park The Shing-Ming Junior LL (Asia-Pacific) defeated the Lufkin LL (Southwest), 2–0, in the final. August 16 – 26: 2018 Little League World Series in South Williamsport at both the Little League Volunteer Stadium and the Howard J. Lamade Stadium The Honolulu LL (West) defeated the South Seoul LL (Asia-Pacific and Middle East), 3–0, in the final.
January 19 – March 25: 2018 FIBA Americas League San Lorenzo defeated Mogi das Cruzes, 79–71, to win their first FIBA Americas League title. Regatas Corrientes took third place. June 11 – 16: 2018 FIBA Under-18 Americas Championship in St. Catharines The United States defeated Canada, 113–74, to win their fifth consecutive and ninth overall FIBA Under-18 Americas Championship title. Argentina took third place. August 1 – 7: 2018 FIBA Under-18 Women's Americas Championship in Mexico City The United States defeated Canada, 84–60, to win their ninth consecutive and tenth overall FIBA Under-18 Women's Americas Championship title. Argentina took third place.
The strong tornado widened again and curved northward as it exited Hodonín and moved into a rural area, completely mowing down a large swath of trees as it impacted a patch of forest. Metal truss transmission towers were blown over in this area, crops were damaged in farm fields, and damage along this segment of the path was rated F2. The tornado briefly strengthened again one final time as it struck the village of Pánov at high-end F3 strength. Almost every structure in the small village was damaged in some way, and multiple homes were significantly damaged or destroyed, a few of which were leveled. Outbuildings were destroyed, cars were damaged by flying debris, and large trees were snapped and denuded as well. The tornado continued past Pánov and moved through another densely forested area, weakening back to F2 strength as it flattened another large swath of trees. The tornado continued to weaken, and trees beyond this point were downed at F1 intensity as the tornado continued to the northeast before it abruptly dissipated near Ratíškovice. In all, at least 1,200 buildings were damaged or destroyed by the tornado along its 27.1 kilometer (17 mi)-long path. 6 people were killed by the tornado, and at least 200 more were injured, some critically.
Sources: en.wikipedia.org
June 13 – 23: 2019 Men's Softball World Championship in Prague-Havlíčkův Brod Argentina defeated Japan, 3–2, to win their first Men's Softball World Championship title. Canada took third place. July 23 – 27: Europe/Africa Softball 2020 Olympic Qualifier in Utrecht Italy defeated Great Britain, 5–0, to book their team and compete at the 2020 Summer Olympics. July 26 – 30: 2019 Women's U12 Softball World Cup in Tainan (debut event) Chinese Taipei defeated Peru, 3–2, to win the inaugural Women's U12 Softball World Cup title. The Czech Republic took third place. Indonesia took fourth place. August 10 – 17: 2019 Women's U19 Softball World Cup in Irvine The United States defeated Japan, 4–3, to win their third consecutive and seventh overall Women's U19 Softball World Cup title. Canada took third place. August 25 – September 1: Americas Softball 2020 Olympic Qualifier in Surrey Champions: Mexico; Second: Canada; Third: Puerto Rico Note: Both Mexico and Canada have qualified to compete at the 2020 Summer Olympics. September 24 –28: Asia/Oceania Softball 2020 Olympic Qualifier in Shanghai Champions: Australia; Second: Chinese Taipei; Third: China Note: Australia has qualified to compete at the 2020 Summer Olympics.
In the evening hours of 24 June 2021, a rare, violent, and deadly long-tracked tornado struck several villages in the Hodonín and Břeclav districts of the South Moravian Region of the Czech Republic, killing six people and injuring 576 others. This tornado is the widest on record in Europe, at 3.5 kilometres (2.2 mi) maximum width. The tornado struck seven municipalities, with the worst damage in the villages of Hrušky, Moravská Nová Ves, Mikulčice and Lužice. This tornado was the strongest ever documented in modern Czech history and the deadliest European tornado since 2001. It was rated as an F4 on the Fujita scale and an IF4 on the International Fujita scale. This made it the first confirmed violent (IF4+) tornado in Europe since June 2017, when an IF4 tornado struck the village of Maloye Pes'yanovo in Russia, until the 2026 Ayyasha-Çaybeyi-Akçamezra tornado on May 3rd 2026, it was the only IF4 rated tornado to occur since the scale was introduced.
5-Hydroxyeicosanoid dehydrogenase (5-HEDH) or more formally, nicotinamide adenine dinucleotide phosphate (NADP+)-dependent dehydrogenase, is an enzyme that metabolizes between two eicosanoid metabolites of arachidonate 5-lipoxygenase (5-LOX): 5-hydroxyeicosatetraenoic acid (5-(S)-HETE), and its 5-keto analog 5-oxo-eicosatetraenoic acid (5-oxo-ETE). It also acts in the reverse direction, metabolizing 5-oxo-ETE to 5(S)-HETE. Since 5-oxo-ETE is 30–100-fold more potent than 5(S)-HETE in stimulating various cell types, 5-HEDH is regarded as a regulator and promoter of the influence that 5-LOX and its metabolites have on cell function. Although 5-HEDH has been evaluated in a wide range of intact cells and in crude microsome preparations, it has not yet been evaluated for its structure or gene, and most studies on it have been limited to human tissues.
July 28 – August 4: 2018 Senior League Baseball World Series in Easley at Easley Recreation Complex The Pariba Little League (Caribbean) defeated the Naamans Little League (East), 7–2, in the final. July 29 – August 5: 2018 Little League Intermediate (50/70) Baseball World Series in Livermore at Max Baer Park The West Seoul LL (Asia-Pacific) defeated the Livermore/Granada LL (Host), 10–0, in the final. August 12 – 19: 2018 Junior League World Series in Taylor at Heritage Park The Shing-Ming Junior LL (Asia-Pacific) defeated the Lufkin LL (Southwest), 2–0, in the final. August 16 – 26: 2018 Little League World Series in South Williamsport at both the Little League Volunteer Stadium and the Howard J. Lamade Stadium The Honolulu LL (West) defeated the South Seoul LL (Asia-Pacific and Middle East), 3–0, in the final.
Sources: en.wikipedia.org
Common methods include enzymatic cycling assays, HPLC with UV detection, and LC-MS. The choice depends on sample size, specificity needs, and available equipment. Rapid quenching before analysis is important because NAD+ and NADH can interconvert.
Water promotes hydrolysis, and heat accelerates degradation. Cold, dry storage slows these processes. Repeated warming and cooling can introduce moisture and condensation, so aliquoting is often used.
Yes. They may be free acid or salts, with different counterions and purity grades. The counterion changes molecular weight, so concentration calculations should account for the actual form. Certificates of analysis provide batch-specific information.
NAD+ and NADH can interconvert quickly after a sample is collected, which can alter the measured ratio. Rapid quenching and cold handling limit enzymatic and chemical changes.