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natural compounds that contain energy-rich bonds.
High-energy compounds are present in all living cells, participating in the processes of energy accumulation and conversion. The compounds are represented mainly by adenosine triphosphate (ATP) and substances capable of ATP formation in enzyme reactions chiefly involving the transfer of phosphate groups. All known high-energy compounds contain either a phosphoryl group () or an acyl group
and are described by the formula
where X is an atom of nitrogen, oxygen, sulfur, or carbon and Y is an atom of phosphorus or carbon. The reactivity of high-energy compounds is related to the increased electrophilicity (affinity for electrons) of the Y atom, which accounts in particular for the high free energy of hydrolysis of the compounds (25.1-58.6 kilojoules per mole [6-14 kilocalories per mole]).
The high-energy compounds also include the nucleoside triphosphoric or diphosphoric acids, the pyrophosphoric and poly-phosphoric acids, phosphocreatine, phosphopyruvic acid, diphosphoglyceric acid, acetyl coenzyme A, succinyl coenzyme A, and the aminoacyl derivatives of adenylic and ribonucleic acids. The compounds are interrelated by their enzyme reactions involving the transfer of phosphoryl groups, in which ATP, a coenzyme in many enzymic reactions, is usually an intermediate product. The overall biological importance of ATP and related high-energy compounds is a function of their central position as links between sources of energy and metabolic processes. They make possible the performance of various types of work, and they play an important role in photosynthesis, bioluminescence, and the synthesis of proteins, fats, carbohydrates, nucleic acids, and other natural compounds.
High-energy compounds should be distinguished from phosphoryl and acyl compounds, which do not contain energy-rich bonds and are therefore incapable of ATP formation in transfer reactions involving phosphoryl and acyl groups (nucleoside monophosphoric acids, nucleic acids, phosphosaccharrides, phospholipides). However, the oxidation of some of these compounds may result in the formation of high-energy compounds.
REFERENCESkulachev, V. P. Akkumuliatsiia energii v kletke. Moscow, 1969.
V. P. SKULACHEV