Adenine nucleotides, which are also sometimes referred to as adenosines or adenylates, are a group of organic molecules including AMP, ADP and ATP. These molecules present the major players of energy storage and transfer.
MitoPedia topics: Substrate and metabolite
Adenine nucleotides and energy transfer
Adenine nucleotides have the typical structure of nucleotides including the purine base adenine attached to a five-carbon sugar and one to three phosphate groups. The three best known members of this family are the purine nucleotides AMP, ADP and ATP, which can be converted into each other by the addition or removal of one to two phosphate groups. This process stores and releases energy by the establishing or breaking of phosphate bonds and is thereby essential for energy transfer and supply of multiple cellular reactions, especially cellular respiration. To restore the energy, an endergonic reaction, in which ATP is created from ADP and a free phosphate is needed. This reaction can be carried out by the membrane embedded ATP synthase (also called complex V). The energy which is used to generate ATP from ADP and Pi is hereby available in the form of hydrogen ions (H+), which are moved down an electrochemical gradient, e.g. from the intermembrane space into the mitochondrial matrix.
Nucleotides are organic molecules and are made up of three subunits: a nitrogenous base (purine or pyrimidine base), a five-carbon sugar (ribose or deoxyribose) and one to three phosphate groups. With this, in short, nucleotides are nucleosides with attached phosphate group(s). Nucleotides present the building blocks of nucleic acids and by this form a part of essential biomolecules of life such as, for example, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). In addition, they make up components that play important roles in biochemical processes, namely nucleoside triphosphates (ATP, GTP, CTP and UTP), which can store and transfer energy (by the conversion of ATP to ADP), or cAMP and cGMP, which participate in cell signalling (cGMP and cAMP). Some nucleotides are also incorporated into important cofactors of enzymatic reactions, for example coenzyme A, FAD, FMN, NAD, and NADP+, and therefore serve essential cellular functions.