Dictionary > Adenosine diphosphate

Adenosine diphosphate


plural: adenosine diphosphates
(biochemistry) A nucleotide made up of adenine, ribose, and two phosphate units; having a chemical formula: C10H15N5O10P2; the product of ATP de-phosphorylation via ATPases to release energy; and can be converted to ATP by phosphorylation (addition of phosphate and energy) via ATP synthases to store energy



A nucleotide is an organic compound made up of three subunits: a nucleobase, a five-carbon sugar, and a phosphate group. The sugar component may either be ribose or deoxyribose. A nucleotide is, thus, a nucleoside with a phosphate group. Depending on the number of phosphate groups attached to the sugar moiety, a nucleotide may be called nucleoside monophosphate (if with only one phosphate group), nucleoside diphosphate (with two phosphate groups), or nucleoside triphosphate (when with three phosphate groups).
Depending on the pentose sugar component, a nucleoside may be a ribonucleoside or a deoxyribonucleoside. A ribonucleoside is a nucleoside with a ribose sugar component. Based on the nucleobase component, the ribonucleoside may be adenosine, guanosine, cytidine, uridine, or 5-methyluridine. A deoxyribonucleoside is a nucleoside with a deoxyribose sugar. Similarly, depending on the nucleobase component, a deoxyribonucleoside may be deoxyadenosine, deoxyguanosine, deoxycytidine, thymidine, or deoxyuridine. Also, depending on the nucleobase component, the nucleosides may be grouped into either the “double-ringed” purine or the “single-ringed” pyrimidine.


Adenosine diphosphate (ADP) is a nucleoside phosphate comprised of a ribonucleoside and two phosphate groups. It means it has a ribose as its sugar and two phosphate groups attached. Its nucleoside contains a purine base, i.e. an adenine attached to the ribose sugar. It has two phosphate groups attached to the nucleoside. The nucleoside is a pentose sugar backbone with a purine base adenine attached to it (at the 1′ carbon). The phosphate groups are bonded in series to the 5′ carbon of the pentose sugar.

Common biological reactions

Common biological reactions

ADP can be derived from adenosine triphosphate (ATP). It can be interconverted to ATP. In particular, ATP is dephosphorylated by ATPases to produce ADP. ADP in turn may be phosphorylated to become ATP. In plants, this conversion of ADP into ATP is enabled via photosynthetic pathways, as light energy is stored as chemical energy in ATP. In animals, energy can be drawn from the breakdown of foodstuff. Glucose from dietary sources, in essence, is used to gather energy via glycolysis, aerobic respiration, and fermentation. The energy is stored especially in the form of ATP. The breakdown of one phosphory bond of ATP can generate about 30.5 kilojoules per mole of ATP.1
ADP can be degraded to produce adenosine monophosphate (AMP, an adenine nucleotide with only one phosphate). Combining two molecules of ADP during ATP synthesis by the action of the enzyme adenylate kinase leads to the formation of AMP: 2 ADP → ATP + AMP.

Biological functions

ADP is essential in photosynthesis and glycolysis. It is the end-product when adenosine triphosphate ATP loses one of its phosphate groups. The energy released in the process is used to power up many vital cellular processes. ADP reconverts to ATP by the addition of a phosphate group to ADP. This occurs in processes such as substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation.
ADP is also important during the activation of platelets. It is stored inside the platelet and is released to interact with ADP receptors (e.g. P2Y1 receptors, P2Y12 receptors, etc.) on platelets.



  • ADP



  • (2R,3S,4R,5R)-5-(6-Aminopurin-9-yl)-3,4-dihydroxyoxolan-2-ylmethyl phosphono hydrogen phosphate


Chemical formula

  • C10H15N5O10P2

Also called


  • adenosine pyrophosphate
  • adenosine 5′-diphosphate
  • adenosine 5′-pyrophosphate
  • adenosine pyrophosphate


Further reading

See also


  1. Farabee, M.J. (2002). “The Nature of ATP”. ATP and Biological Energy on the Internet. Archived from the original on 2007-12-01.

© Biology Online. Content provided and moderated by Biology Online Editors

You will also like...

Sugar Homeostasis
Sugar Homeostasis

The blood sugar level is regulated by two hormones. The mechanism behind this type of negative feedback control is descr..

Primitive Animals

Life, as we know it today, is presumed to have started in the sea and many of them were likely eukaryotic animal-like or..

Regulation of Biological Systems
Regulation of Biological Systems

Regulation of Biological Systems tutorials are focused on the modulation of biological systems from cell to population l..

Gene Regulation in Eukaryotes
Gene Regulation in Eukaryotes

Learn about the general structure of a eukaryotic gene, the transcription factors, and post-transcriptional regulation....

Early Mammals on Earth
Early Mammals on Earth

The Earth's ecosphere was rapidly changing and throwing up a wide range of ecological niches that new adaptive organisms..

Disturbance on a still water
Abiotic Factors – Water Conditions

A still body of water may be disturbed by a variety of factors. One of them is wind. In fact, it is considered as the pr..