LC-MS raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-01-15 and is reviewed periodically as new material appears.
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.
NAD+ is a dinucleotide composed of nicotinamide, ribose, and adenine linked by phosphate groups. Its full name is nicotinamide adenine dinucleotide, with "+" denoting the oxidized form. The molecule acts as a coenzyme in redox reactions, cycling between NAD+ and NADH. In cells, it participates in electron transfer during glycolysis, the citric acid cycle, and oxidative phosphorylation. It is distinct from NADP+, which carries an additional phosphate group and supports different biosynthetic reactions.
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 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.
| Property | Value | Notes |
|---|---|---|
| Common name | Nicotinamide adenine dinucleotide (oxidized) | Often shortened to NAD+ |
| Chemical class | Dinucleotide | Contains nicotinamide and adenine moieties |
| Molecular formula | C21H27N7O14P2 | Free acid form; charge depends on pH |
| Molar mass | About 663.43 g/mol | Calculated for C21H27N7O14P2 |
| CAS number | 53-84-9 | Common identifier for beta-NAD+ |
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.
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.
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.
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.
Stability studies show that NAD+ can hydrolyze under prolonged heat, extreme pH, or microbial contamination. Phosphate buffers near neutral pH are often used for short-term handling, though exact stability depends on concentration, temperature, and matrix. In biological samples, endogenous enzymes can rapidly degrade NAD+, making cold chain and fast processing important. Analytical reports should state extraction conditions, internal standards, and validation parameters. Without those details, comparisons across studies remain difficult and potentially misleading.
Laboratory measurement of NAD+ often begins with rapid quenching of cell or tissue samples to prevent enzymatic conversion. Acidic or alkaline extraction can precipitate proteins, but the chosen method affects recovery of oxidized and reduced forms. Enzymatic cycling assays provide high sensitivity by amplifying a NAD+-dependent reaction. High-performance liquid chromatography and mass spectrometry offer separation and structural confirmation. Each method has trade-offs in throughput, specificity, and the ability to distinguish NAD+ from close analogues.
Purified NAD+ is typically supplied as a white to off-white powder and stored desiccated at low temperature. Airtight containers limit moisture uptake, while protection from light reduces degradation of the nicotinamide ring. Aqueous stock solutions are less stable than solid material and are often aliquoted before freezing. Repeated freeze-thaw cycles can lower integrity, so working portions are kept separate. Purity is commonly checked by ultraviolet absorbance near 260 nm, high-performance liquid chromatography, or mass spectrometry.
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 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.
== Personal life == On November 11, 1932, he married the socially connected Blanchette Ferry Hooker (1909–1992), who was to serve as chairman of the Asian Cultural Council from 1980 to 1990, and who established the Blanchette H. Rockefeller Fellowship Fund, in Japan. They had one son and three daughters:
==== 1.A α-type channels ==== 1.A.1 Voltage-gated ion channel superfamily 1.A.2 Inward-rectifier K+ channel family 1.A.3 Ryanodine-inositol-1,4,5-trisphosphate receptor Ca2+ channel family 1.A.4 Transient receptor potential Ca2+ channel family 1.A.5 Polycystin cation channel family 1.A.6 Epithelial Na+ channel family 1.A.7 ATP-gated P2X receptor cation channel family 1.A.8 Major intrinsic protein superfamily 1.A.9 Neurotransmitter receptor, Cys loop, ligand-gated ion channel family 1.A.10 Glutamate-gated ion channel family of neurotransmitter receptors 1.A.11 Ammonium channel transporter family 1.A.12 Intracellular chloride channel family 1.A.13 Epithelial chloride channel family 1.A.14 Testis-enhanced gene transfer family 1.A.15 Nonselective cation channel-2 family 1.A.16 Formate-nitrite transporter family 1.A.17 Calcium-dependent chloride channel family 1.A.18 Chloroplast envelope anion-channel-forming Tic110 family 1.A.19 Type A influenza virus matrix-2 channel family 1.A.20 BCL2/Adenovirus E1B-interacting protein 3 family 1.A.21 Bcl-2 family 1.A.22 Large-conductance mechanosensitive ion channel 1.A.23 Small-conductance mechanosensitive ion channel 1.A.24 Gap-junction-forming connexin family 1.A.25 Gap-junction-forming innexin family 1.A.26 Mg2+ transporter-E family 1.A.27 Phospholemman family 1.A.28 Urea transporter family 1.A.29 Urea/amide channel family 1.A.30 H+- or Na+-translocating bacterial MotAB flagellar motor/ExbBD outer-membrane transport energizer superfamily 1.A.31 Annexin family 1.A.32 Type B influenza virus NB channel family 1.A.33 Cation-channel-forming heat shock protein 70 family 1.A.34 Bacillus gap junction-like channel-forming complex family 1.A.35 CorA metal ion transporter family 1.A.36 Intracellular chloride channel family 1.A.37 CD20 Ca2+ channel family 1.A.38 Golgi pH regulator family 1.A.39 Type C influenza virus CM2 channel family 1.A.40 Human immunodeficiency virus type I Vpu channel family 1.A.41 Avian reovirus p10 Vvroporin family 1.A.42 HIV viral protein R family 1.A.43 Camphor resistance or fluoride exporter family 1.A.44 Pore-forming tail Tip pb2 protein of phage T5 family 1.A.45 Phage P22 injectisome family 1.A.46 Anion channel-forming bestrophin family 1.A.47 Nucleotide-sensitive anion-selective channel, ICln family 1.A.48 Anion channel Tweety family 1.A.49 Human coronavirus ns12.9 viroporin family 1.A.50 Phospholamban (Ca2+-channel and Ca2+-ATPase regulator) family 1.A.51 The Voltage-gated Proton Channel (VPC) Family 1.A.52 The Ca2+ Release-activated Ca2+ (CRAC) Channel (CRAC-C) Family 1.A.53 The Hepatitis C Virus P7 Viroporin Cation-selective Channel (HCV-P7) Family 1.A.54 The Presenilin ER Ca2+ Leak Channel (Presenilin) Family 1.A.55 The Synaptic Vesicle-Associated Ca2+ Channel, Flower (Flower) Family 1.A.56 The Copper Transporter (Ctr) Family 1.A.57 The Human SARS Coronavirus Viroporin (SARS-VP) 1.A.58 The Type B Influenza Virus Matrix Protein 2 (BM2-C) Family 1.A.59 The Bursal Disease Virus Pore-Forming Peptide, Pep46 (Pep46) Family 1.A.60 The Mammalian Reovirus Pre-forming Peptide, Mu-1 (Mu-1) Family 1.A.61 The Insect Nodavirus Channel-forming Chain F (Gamma-Peptide) Family 1.A.62 The Homotrimeric Cation Channel (TRIC) Family 1.A.63 The Ignicoccus Outer Membrane α-helical Porin (I-OMP Family 1.A.64 The Plasmolipin (Plasmolipin) Family 1.A.65 The Coronavirus Viroporin E Protein (Viroporin E) Family 1.A.66 The Pardaxin (Pardaxin) Family 1.A.67 The Membrane Mg2+ Transporter (MMgT) Family 1.A.68 The Viral Small Hydrophobic Viroporin (V-SH) Family 1.A.69 The Heteromeric Odorant Receptor Channel (HORC) Family 1.A.70 The Molecule Against Microbes A (MamA) Family 1.A.71 The Brain Acid-soluble Protein Channel (BASP1 Channel) Family 1.A.72 The Mer Superfamily 1.A.73 The Colicin Lysis Protein (CLP) Family 1.A.74 The Mitsugumin 23 (MG23) Family 1.A.75 The Mechanical Nociceptor, Piezo (Piezo) Family 1.A.76 The Magnesium Transporter1 (MagT1) Family 1.A.77 The Mg2+/Ca2+ Uniporter (MCU) Family 1.A.78 The K+-selective Channel in Endosomes and Lysosomes (KEL) Family 1.A.79 The Cholesterol Uptake Protein (ChUP) or Double Stranded RNA Uptake Family 1.A.80 The NS4a Viroporin (NS4a) Family 1.A.81 The Low Affinity Ca2+ Channel (LACC) Family 1.A.82 The Hair Cell Mechanotransduction Channel (HCMC) Family 1.A.83 The SV40 Virus Viroporin VP2 (SV40 VP2) Family 1.A.84 The Calcium Homeostasis Modulator Ca2+ Channel (CALHM-C) Family 1.A.85 The Poliovirus 2B Viroporin (2B Viroporin) Family 1.A.86 The Human Papilloma Virus type 16 (HPV16) L2 Viroporin (L2 Viroporin) Family 1.A.87 The Mechanosensitive Calcium Channel (MCA) Family 1.A.88 The Fungal Potassium Channel (F-Kch) Family 1.A.89 The Human Coronavirus 229E Viroporin (229E Viroporin) Family 1.A.90 The Human Metapneumovirus (HMPV) Viroporin (HMPV-Viroporin) Family 1.A.91 The Cytoadherence-linked Asexual Protein 3.2 of Plasmodium falciparum (Clag3) Family 1.A.92 The Reovirus Viroporin VP10 (RVP10) Family 1.A.93 The Bluetongue Virus Non-Structural Protein 3 Viroporin (NS3) Family 1.A.94 The Rotavirus Non-structural Glycoprotein 4 Viroporin (NSP4) Family 1.A.95 The Ephemerovirus Viroporin (EVVP) Family 1.A.96 The Human Polyoma Virus Viroporin (PVVP) Family 1.A.97 The Human Papillomavirus type 16 E5 Viroporin (HPV-E5) Family 1.A.98 Human T-Lymphotropic Virus 1 P13 protein (HTLV1-P13) Family 1.A.99 The Infectious Bronchitis Virus Envelope Small Membrane Protein E (IBV-E) Family 1.A.100 The Rhabdoviridae Putative Viroporin, U5 (RV-U5) Family 1.A.101 The Peroxisomal Pore-forming Pex11 (Pex11) Family 1.A.102 Influenza A viroporin PB1-F2 (PB1-F2) Family 1.A.103 The Simian Virus 5 (Parainfluenza Virus 5) SH (SV5-SH) Family 1.A.104 The Proposed Flagellar Biosynthesis Na+ Channel, FlaH (FlaH) Family 1.A.105 The Mixed Lineage Kinase Domain-like (MLKL) Family 1.A.106 The Calcium Load-activated Calcium Channel (CLAC) Family 1.A.107 The Pore-forming Globin (Globin) Family
In 1867, the Austro-Hungarian compromise and the introduction of the dual monarchy left the Czechs and their aristocracy without the recognition of separate Bohemian state rights for which they had hoped. Bohemia remained part of the Austrian Crown Lands. In Bohemia, opposition to dualism took the form of isolated street demonstrations, resolutions from district representations, and even open air mass protest meetings, confined to the biggest cities, such as Prague. The Czech newspaper Národní listy complained that the Czechs had not yet been compensated for their wartime losses and sufferings during the Austro-Prussian War, and had just seen their historic state rights tossed aside and their land subsumed into the "other" half of the Austro-Hungarian Monarchy, commonly called "Cisleithania". The Czech hopes were revived again in 1870–1871. In an Imperial Rescript of 26 September 1870, Franz Joseph referred again to the prestige and glory of the Bohemian Crown and to his intention to hold a coronation. Under Minister-President Karl Hohenwart in 1871, the government of Cisleithania negotiated a series of fundamental articles spelling out the relationship of the Bohemian Crown to the rest of the Habsburg Monarchy. On 12 September 1871, Franz Joseph announced:
Resistin, also known as adipose tissue-specific secretory factor (ADSF) or C/EBP-epsilon-regulated myeloid-specific secreted cysteine-rich protein (XCP1), is a cysteine-rich peptide hormone that is derived from adipose tissue and, in humans, is encoded by the RETN gene. In primates, pigs, and dogs, resistin is secreted primarily by immune and epithelial cells, whereas in rodents, it is mainly secreted by adipose tissue. The human resistin pre-peptide consists of 108 amino acid residues, while in mice and rats it is 114 amino acids in length; the molecular weight is approximately 12.5 kDa. Resistin is classified as an adipose-derived hormone (similar to a cytokine), and its physiological role has been widely debated, particularly regarding its involvement in obesity and type II diabetes mellitus (T2DM).
Fentanyl and fentanyl analogues can be qualitatively detected in drug samples using commercially available fentanyl testing strips or spot reagents. Following the principles of harm reduction, this test is to be used directly on drug samples as opposed to urine. To prepare a sample for testing, approximately 10 mg of the drug should be diluted into 1 tsp (5 mL) of water. Research in Dr. Lieberman's lab at the University of Notre Dame has reported false positive results on BTNX fentanyl testing strips with methamphetamine, MDMA, and diphenhydramine. The sensitivity and specificity of fentanyl test strips vary depending on the concentration of fentanyl tested, particularly from 10 to 250 ng/mL.
Sources: en.wikipedia.org
== Awards == Wennemers work was recognized by the Leonidas Zervas Award of the European Peptide Society (2010), the Pedler Award of the Royal Society of Chemistry (2016), the Inhoffen Medal (2017), the Netherlands Scholar Award for Supramolecular Chemistry (2019), the Arthur C. Cope Scholar Award of the American Chemical Society (2021), the Scoffone Prize of the Italian Peptide Society (2022), and the Vincent du Vigneaud Award of the American Peptide Society (2023). She also won ths 2020 Spark Award (invention) and the 2023 Golden Owl Award (teaching) from the ETH Zurich. Wennemers was awarded the Emil Fischer Medal by the German Chemical Society on September 7, 2026, for her pioneering work on synthetic peptides, becoming the first woman to win the award in its 114-year history.
Fully aquatic mammals, the cetaceans and sirenians, have lost their legs and have a tail fin to propel themselves through the water. Flipper movement is continuous. Whales swim by moving their tail fin and lower body up and down, propellling themselves through vertical movement, while their flippers are mainly used for steering. Their skeletal anatomy allows them to be fast swimmers. Most species have a dorsal fin to prevent themselves from turning upside-down in the water. The flukes of sirenians are raised up and down in long strokes to move the animal forward, and can be twisted to turn. The forelimbs are paddle-like flippers which aid in turning and slowing. Semi-aquatic mammals, like pinnipeds, have two pairs of flippers on the front and back, the fore-flippers and hind-flippers. The elbows and ankles are enclosed within the body. Pinnipeds have several adaptions for reducing drag. In addition to their streamlined bodies, they have smooth networks of muscle bundles in their skin that may increase laminar flow and make it easier for them to slip through water. They also lack arrector pili, so their fur can be streamlined as they swim. They rely on their fore-flippers for locomotion in a wing-like manner similar to penguins and sea turtles. Fore-flipper movement is not continuous, and the animal glides between each stroke. Compared to terrestrial carnivorans, the fore-limbs are reduced in length, which gives the locomotor muscles at the shoulder and elbow joints greater mechanical advantage; the hind-flippers serve as stabilizers.
=== Health and death === On September 16, 1999, Barker was in Washington, D.C., to testify before Congress regarding proposed legislation that would ban captive elephants from traveling shows, such as circuses. While preparing for the presentation, Barker experienced what he called clumsiness in his right hand. Barker was admitted to George Washington University Hospital and diagnosed with a partially blocked left carotid artery. He underwent carotid endarterectomy to remove the blockage. The procedure went well enough that Barker was able to return to work within the month. Three years later, Barker had two additional health crises after taping the 30th-season finale of The Price is Right. While lying in the sun on May 30, 2002, he experienced a stroke and was hospitalized; six weeks later, on July 11, Barker underwent prostate surgery. Both hospitalizations occurred at George Washington University Hospital in Washington, D.C. and both surgeries were successful. Barker had several mild bouts with skin cancer, a result of his frequent tanning. Barker consulted a dermatologist regularly to make sure any cancers were caught and removed before they spread; they did not pose a threat to his life. During a televised interview, Barker told viewers, "I urge anyone who has spent some time in the sun, whether you're doing it now or not, go to a dermatologist once a year." On October 20, 2015, two police officers passing Barker's Los Angeles-area home saw him trip and fall on a sidewalk.
She played the role of Amelia Slater in the Fox series Pitch, about Ginny Baker (Kylie Bunbury), a young black woman who makes history by becoming the first woman to play for a Major League Baseball team. The series ran for a season, which was released in 2016. From 2019 to 2020, Larter acted in the recurring role of Grace Sawyer in the police procedural series The Rookie on ABC In 2021, she played the lead role in the neo-western film The Last Victim. She starred in the thriller The Man in the White Van, which premiered at the 2023 Newport Beach Film Festival and was released in December 2024 to mixed reviews. In 2024, Larter co-starred in Taylor Sheridan’s show Landman, starring Billy Bob Thornton. Larter plays Angela Norris, a “cartoonish” funny caricature of a gold-digging ex-wife.
They also stressed that the TWG had given too much credence to the chemistry experiments performed by the Russians, considered the TWG's retrospective treatment of the Russian work based on unpublished documents to have been "highly irregular", noted that there was no proof that 259Rf had a spontaneous fission branch at all (as of 2021 there still is not), and accused the TWG of not having appropriately qualified personnel on the committee. The TWG responded by saying that this was not the case and having assessed each point raised by the American group said that they found no reason to alter their conclusion regarding priority of discovery. The International Union of Pure and Applied Chemistry (IUPAC) adopted unnilquadium (Unq) as a temporary, systematic element name, derived from the Latin names for digits 1, 0, and 4. In 1994, IUPAC suggested a set of names for elements 104 through 109, in which dubnium (Db) became element 104 and rutherfordium became element 106. This recommendation was criticized by the American scientists for several reasons. Firstly, their suggestions were scrambled: the names rutherfordium and hahnium, originally suggested by Berkeley for elements 104 and 105, were respectively reassigned to elements 106 and 108. Secondly, elements 104 and 105 were given names favored by JINR, despite earlier recognition of LBL as an equal co-discoverer for both of them.
Sources: en.wikipedia.org
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.
No. NAD+ is the oxidized form and NADH is the reduced form. They differ by two electrons and a proton equivalent, and cells interconvert them during metabolism.
Yes. NAD+ is present in all living cells and is required for fundamental metabolic reactions. Its concentration varies by tissue, compartment, and time.
It indicates a formal positive charge on the nicotinamide ring. The molecule is not simply a protonated acid, and the charge is part of its redox chemistry.