Adenosine diphosphate, abbreviated ADP, is a nucleotide. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate group, the pentose sugar ribose, and the nucleobase adenine.
ADP is the product of ATP dephosphorylation by ATPases. ADP is converted back to ATP by ATP synthases. ATP is an important energy transfer molecule in cells.
ADP is stored in dense bodies inside blood platelets and is released upon platelet activation. ADP interacts with a family of ADP receptors found on platelets (P2Y1, P2Y12 and P2X1), leading to further platelet activation. ADP in the blood is converted to adenosine by the action of ecto-ADPases, inhibiting further platelet activation via adenosine receptors. The anti-platelet drug Plavix (clopidogrel) inhibits the P2Y12 receptor.
ADP is the end-product that results when ATP loses one of its phosphate groups located at the end of the molecule. The conversion of these two molecules plays a critical role in supplying energy for many processes of life. The deletion of one of ATP’s phosphorus bonds generates approximately 7.3 kilocalories per Mole of ATP. ADP can be converted, or powered back to ATP through the process of releasing the chemical energy available in food; in humans this is constantly performed via aerobic respiration in the mitochondria. Plants use photosynthetic pathways to convert and store the energy from sunlight, via conversion of ADP to ATP. Animals use the energy released in the breakdown of glucose and other molecules to convert ADP to ATP, which can then be used to fuel necessary growth and cell maintenance. Recently Dr.Atul Kumar for the first time demonstrated that single nucleotides (ADP}have the ability to catalyze organic reactions, and performed Biomimetic reductive amination, which is considered as one of the most genuine biomimetic reactions of organic chemistry. This single-nucleotide catalysis has immense impact on many fields of science such as chemistry, biochemistry, and prebiotic studies, especially the RNA world and DNA world hypothesis for understanding the origin of life on Earth.
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