Interactive animation of the structure of ATP
The succinate dehydrogenase complex showing several cofactors, including flavin, iron–sulfur centers, and heme.
The cycles of synthesis and degradation of ATP; 2 and 1 represent input and output of energy, respectively.
A simple [Fe2S2] cluster containing two iron atoms and two sulfur atoms, coordinated by four protein cysteine residues.
This image shows a 360-degree rotation of a single, gas-phase magnesium-ATP chelate with a charge of −2. The anion was optimized at the UB3LYP/6-311++G(d,p) theoretical level and the atomic connectivity modified by the human optimizer to reflect the probable electronic structure.
The redox reactions of nicotinamide adenine dinucleotide.
An example of the Rossmann fold, a structural domain of a decarboxylase enzyme from the bacterium Staphylococcus epidermidis with a bound flavin mononucleotide cofactor.

It is also a precursor to DNA and RNA, and is used as a coenzyme.

- Adenosine triphosphate

Many contain the nucleotide adenosine monophosphate (AMP) as part of their structures, such as ATP, coenzyme A, FAD, and NAD+.

- Cofactor (biochemistry)
Interactive animation of the structure of ATP

4 related topics


The redox reactions of nicotinamide adenine dinucleotide.

Nicotinamide adenine dinucleotide

The redox reactions of nicotinamide adenine dinucleotide.
UV absorption spectra of NAD and NADH.
Some metabolic pathways that synthesize and consume NAD in vertebrates. The abbreviations are defined in the text.
Salvage pathways use three precursors for NAD+.
Rossmann fold in part of the lactate dehydrogenase of Cryptosporidium parvum, showing NAD in red, beta sheets in yellow, and alpha helices in purple.
In this diagram, the hydride acceptor C4 carbon is shown at the top. When the nicotinamide ring lies in the plane of the page with the carboxy-amide to the right, as shown, the hydride donor lies either "above" or "below" the plane of the page. If "above" hydride transfer is class A, if "below" hydride transfer is class B.
A simplified outline of redox metabolism, showing how NAD and NADH link the citric acid cycle and oxidative phosphorylation.
The structure of cyclic ADP-ribose.
Arthur Harden, co-discoverer of NAD

Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism.

This contrasts with eukaryotic DNA ligases, which use ATP to form the DNA-AMP intermediate.

Summary of aerobic respiration


Metabolic pathway that converts glucose , into pyruvic acid (CH3COCO2H).

Metabolic pathway that converts glucose , into pyruvic acid (CH3COCO2H).

Summary of aerobic respiration
Summary of the 10 reactions of the glycolysis pathway
Glycolysis pathway overview.
Eduard Buchner. Discovered cell-free fermentation.
Otto Meyerhof. One of the main scientists involved in completing the puzzle of glycolysis
Yeast hexokinase B
Bacillus stearothermophilus phosphofructokinase
Yeast pyruvate kinase

The free energy released in this process is used to form the high-energy molecules adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH).

Arthur Harden and William Young along with Nick Sheppard determined, in a second experiment, that a heat-sensitive high-molecular-weight subcellular fraction (the enzymes) and a heat-insensitive low-molecular-weight cytoplasm fraction (ADP, ATP and NAD+ and other cofactors) are required together for fermentation to proceed.

Simplified view of the cellular metabolism


Set of life-sustaining chemical reactions in organisms.

Set of life-sustaining chemical reactions in organisms.

Simplified view of the cellular metabolism
Structure of adenosine triphosphate (ATP), a central intermediate in energy metabolism
Structure of a triacylglycerol lipid
This is a diagram depicting a large set of human metabolic pathways.
Glucose can exist in both a straight-chain and ring form.
Structure of the coenzyme acetyl-CoA.The transferable acetyl group is bonded to the sulfur atom at the extreme left.
The structure of iron-containing hemoglobin. The protein subunits are in red and blue, and the iron-containing heme groups in green. From.
A simplified outline of the catabolism of proteins, carbohydrates and fats
Mechanism of ATP synthase. ATP is shown in red, ADP and phosphate in pink and the rotating stalk subunit in black.
Plant cells (bounded by purple walls) filled with chloroplasts (green), which are the site of photosynthesis
Simplified version of the steroid synthesis pathway with the intermediates isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP) and squalene shown. Some intermediates are omitted for clarity.
Effect of insulin on glucose uptake and metabolism. Insulin binds to its receptor (1), which in turn starts many protein activation cascades (2). These include: translocation of Glut-4 transporter to the plasma membrane and influx of glucose (3), glycogen synthesis (4), glycolysis (5) and fatty acid synthesis (6).
Evolutionary tree showing the common ancestry of organisms from all three domains of life. Bacteria are colored blue, eukaryotes red, and archaea green. Relative positions of some of the phyla included are shown around the tree.
Metabolic network of the Arabidopsis thaliana citric acid cycle. Enzymes and metabolites are shown as red squares and the interactions between them as black lines.
Aristotle's metabolism as an open flow model
Santorio Santorio in his steelyard balance, from Ars de statica medicina, first published 1614

These group-transfer intermediates are called coenzymes.

One central coenzyme is adenosine triphosphate (ATP), the universal energy currency of cells.

Reaction of FAD to form FADH2

Flavin adenine dinucleotide

Reaction of FAD to form FADH2
Approximate absorption spectrum for FAD
Mechanism 1. Hydride transfer occurs by addition of H+ and 2 e−
Mechanism 2. Hydride transfer by abstraction of hydride from NADH
Mechanism 3. Radical formation by electron abstraction
Mechanism 4. The loss of hydride to electron deficient R group
Mechanism 5. Use of nucleophilic addition to break R1-R2 bond
Mechanism 6. Carbon radical reacts with O2 and acid to form H2O2

In biochemistry, flavin adenine dinucleotide (FAD) is a redox-active coenzyme associated with various proteins, which is involved with several enzymatic reactions in metabolism.

Warburg's work with linking nicotinamide to hydride transfers and the discovery of flavins paved the way for many scientists in the 40s and 50s to discover copious amounts of redox biochemistry and link them together in pathways such as the citric acid cycle and ATP synthesis.