The hydrolysis of ATP into ADP and inorganic phosphate releases 20.5 kJ/mol of enthalpy. In the context of biochemical reactions, the P-O-P bonds are frequently referred to as high-energy bonds. Living cells maintain the ratio of ATP to ADP at a point ten orders of magnitude from equilibrium, with ATP concentrations fivefold higher than the concentration of ADP. At more extreme pHs, it rapidly hydrolyses to ADP and phosphate. The cycles of synthesis and degradation of ATP 2 and 1 represent input and output of energy, respectively.ĪTP is stable in aqueous solutions between pH 6.8 and 7.4, in the absence of catalysts. Salts of ATP can be isolated as colorless solids. The presence of Mg 2+ regulates kinase activity. Ī second magnesium ion is critical for ATP binding in the kinase domain. Due to the strength of the ATP-Mg 2+ interaction, ATP exists in the cell mostly as a complex with Mg 2+īonded to the phosphate oxygen centers. The binding of a divalent cation, almost always magnesium, strongly affects the interaction of ATP with various proteins. Binding of metal cations to ATP īeing polyanionic and featuring a potentially chelating polyphosphate group, ATP binds metal cations with high affinity. In neutral solution, ionized ATP exists mostly as ATP 4−, with a small proportion of ATP 3−. The three phosphoryl groups are labeled as alpha (α), beta (β), and, for the terminal phosphate, gamma (γ). In its many reactions related to metabolism, the adenine and sugar groups remain unchanged, but the triphosphate is converted to di- and monophosphate, giving respectively the derivatives ADP and AMP. It is also a precursor to DNA and RNA, and is used as a coenzyme.įrom the perspective of biochemistry, ATP is classified as a nucleoside triphosphate, which indicates that it consists of three components: a nitrogenous base ( adenine), the sugar ribose, and the triphosphate.ĪTP consists of an adenine attached by the 9-nitrogen atom to the 1′ carbon atom of a sugar ( ribose), which in turn is attached at the 5' carbon atom of the sugar to a triphosphate group. The human body recycles its own body weight equivalent in ATP each day. When consumed in metabolic processes, it converts either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Found in all known forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer. Interactive animation of the structure of ATPĪdenosine triphosphate ( ATP) is an organic compound that provides energy to drive and support many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis.
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