This is a working overview of ADP-ribose, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-30 and is reviewed periodically as new material appears.
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.
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.
Commercial NAD+ is supplied as a solid, often as the free acid or a salt, and purity is verified by chromatographic methods. Laboratories typically store it desiccated at minus 20 degrees Celsius or below. Working solutions are prepared fresh because even sterile aqueous solutions can lose activity over hours to days depending on pH and temperature. Documentation may include a certificate of analysis, an assay value, and a recommended retest date. Researchers should verify identity and purity when results depend on precise cofactor concentrations.
| Property | Value | Notes |
|---|---|---|
| Chemical name | Nicotinamide adenine dinucleotide (oxidized form) | NAD+ denotes the oxidized redox state |
| Common synonyms | Diphosphopyridine nucleotide; coenzyme I | Older names appear in historical literature |
| Molar mass | About 663.43 g/mol | Free acid value; salts and hydrates differ |
| Appearance | White to off-white powder | The purified solid is white; solutions are clear |
| Solubility | Highly soluble in water | Aqueous buffers are common laboratory solvents |
NAD+ stands for nicotinamide adenine dinucleotide, the oxidized form of a coenzyme found in all living cells. The molecule consists of two nucleotides, adenine and nicotinamide ribose, joined through phosphate groups. Its chemical formula is C21H27N7O14P2, and the free acid has a molar mass near 663.43 grams per mole. In redox reactions, NAD+ accepts a hydride ion and becomes NADH. The pair NAD+ and NADH participates in hundreds of metabolic reactions, including steps in glycolysis, the citric acid cycle, and oxidative phosphorylation.
In cells, NAD+ functions primarily as an electron carrier. Dehydrogenase enzymes in glycolysis and the citric acid cycle transfer hydride from substrates to NAD+, producing NADH. NADH then delivers electrons to the mitochondrial respiratory chain, supporting ATP synthesis. In fermentation, NADH is reoxidized to NAD+ so that glycolysis can continue. The balance between NAD+ and NADH helps set metabolic flux. Beyond redox, NAD+ serves as a substrate for enzymes that cleave it, including sirtuins, poly(ADP-ribose) polymerases, and CD38. These reactions consume NAD+ and release nicotinamide and ADP-ribose products.
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.
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.
The stability of NAD+ depends on pH, temperature, light exposure, and the presence of degradative enzymes. Aqueous solutions are generally more stable under mildly acidic to neutral conditions and degrade faster under alkaline conditions or prolonged heat. The solid is hygroscopic and should be stored desiccated, often frozen, and protected from repeated freeze-thaw cycles. In laboratory handling, aliquots reduce repeated temperature changes, and chelating agents may limit metal-catalyzed hydrolysis in some buffers. These practices matter because even small amounts of NADH or hydrolysis products can interfere with quantitative assays.
Quality control for NAD+ materials typically combines identity, purity, and water content checks. Identity may be confirmed by ultraviolet spectrum, retention time in chromatography, or mass accuracy, while purity is assessed by HPLC peak area or quantitative nuclear magnetic resonance. Residual water and solvents can affect molar calculations and enzyme assays, so Karl Fischer titration or thermogravimetric analysis may be used. Commercial materials vary in grade and counterion form, and published methods should specify the exact salt or hydrate when reporting concentrations. Regulatory status depends on intended use, with research reagents, dietary ingredients, and clinical products treated under different frameworks.
Niacin as a chemical compound was first described by chemist Hugo Weidel in 1873 in his studies of nicotine, but that predated by many years the concept of food components other than protein, fat and carbohydrates that were essential for life. Vitamin nomenclature was initially alphabetical, with Elmer McCollum calling these fat-soluble A and water-soluble B. Over time, eight chemically distinct, water-soluble B vitamins were isolated and numbered, with niacin as vitamin B3.
Jain communities established large-scale systems for animal welfare long ago. Jain merchants funded the creation of panjrapoles—specialized animal shelters and hospitals across India designed to care for sick, old, or rescued livestock and birds. The motivation behind these early shelters was not modern ethical philosophy, but the core Jain religious belief that committing violence against any living creature directly harms a person's own soul and spiritual purity. Ethical vegetarianism has become popular in developed countries particularly because of the spread of factory farming and environmental consciousness. Some believe that the current mass-demand for meat cannot be satisfied without a mass-production system that disregards the welfare of animals, while others believe that practices like well-managed free-range farming or the consumption of game (particularly from species whose natural predators have been significantly eliminated) could substantially alleviate consumer demand for mass-produced meat.
=== Nanotechnologies used in vitamin B12 supplementation === Conventional administration does not ensure specific distribution and controlled release of vitamin B12, for example to bone marrow and nerve cells. Nanocarrier strategies for improved vitamin B12 delivery remain embryonic as of 2021.
Sources: en.wikipedia.org
C. brunneus produce song by moving stridulatory pegs against their elytra. The normal calling song consists of 5-12 notes that range between 0.25 and 0.50 seconds in length. Notes are followed by a 3-second period of rest. Males will repeat the song at intervals. Males produce a rival song when they come into contact with other males. C. brunneus males produce sounds during the pauses of the other males' song. Notes in the rival song are produced three to four times faster than notes produced in the normal song. In the normal song notes are produced every 1.5–2 seconds but in the rival song notes are produced every 0.35–0.57 seconds. Courtship songs are produced after the male produces some notes from his normal song and fails to copulate. Courtship songs in C. brunneus consist of softer notes similar to the normal song produced at higher frequencies. After producing the song for a duration the male will attempt to copulate with the female. If he is unsuccessful he will produce several short, loud notes before producing the courtship song again. A receptive female will respond to the male's song leading to the alteration of song between her and the male. This is called the attraction song. Male C. brunneus not only produce several different types of calls, they also show variation in characteristics of the same song. Stabilizing selection has acted on male C. brunneus song. Males with intermediate song characteristics are most successful while males with extreme characteristics are the least successful in attracting a mate. Song production is sensitive to the environment.
The 23S rRNA is a 2,904 nucleotide long (in E. coli) component of the large subunit (50S) of the bacterial/archean ribosome and makes up the peptidyl transferase center (PTC). The 23S rRNA is divided into six secondary structural domains titled I-VI, with the corresponding 5S rRNA being considered domain VII. The ribosomal peptidyl transferase activity resides in domain V of this rRNA, which is also the most common binding site for antibiotics that inhibit translation, making it a target for ribosomal engineering. A well-known member of this antibiotic class, chloramphenicol, acts by inhibiting peptide bond formation, with recent 3D-structural studies showing two different binding sites depending on the species of ribosome. Numerous mutations in domains of the 23S rRNA with Peptidyl transferase activity have resulted in antibiotic resistance. 23S rRNA genes typically have higher sequence variations, including insertions and/or deletions, compared to other rRNAs. The eukaryotic homolog of the 23S LSU rRNA is the 28S ribosomal RNA, with a region filled by the 5.8S ribosomal RNA.
== History == Sauk City restaurateurs and husband and wife team George and Ruth Culver started their fast food careers as the owners of an A&W on Phillips Boulevard (U.S. Highway 12) in 1961. In 1968, they purchased a resort-styled restaurant at Devil's Lake called The Farm Kitchen. Their son, Craig Culver, worked for a local McDonald's right out of college in 1973. George, Ruth, their son Craig, and his wife Lea opened the first Culver's Frozen Custard and ButterBurgers in Sauk City, Wisconsin on July 18, 1984. Craig was CEO of Culver's from its inception until mid-2015.
Sources: en.wikipedia.org
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.
NAD+ is the oxidized form, while NADH is the reduced form carrying two additional electrons and a proton. The two forms interconvert in many metabolic reactions.
No. NADP+ contains an extra phosphate group on the adenine ribose. NADP+ and NADPH tend to participate in different biosynthetic and antioxidant pathways.
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.