From Big Medical Encyclopedia


the chemical changes which are followed by increase in free energy (AG), i.e. reaction in to-rykh a difference between free energy of formation of reaction products and free energy of formation of mother substances is size positive. It is spontaneous to the reaction capable to proceed in the return for specific E. rubles the direction and characterized by the negative size of standard free energy (A G °), are called ekzergonichesky. Example E. the river can serve having exclusive value in a metabolism and energy (see) reaction of phosphorylation of ADF with formation of ATP (see Adenozinfosforny acids, Phosphorylation). With a constant pressure and temperature E. the river (so-called isobarometric processes) cannot spontaneously flow as, according to the second law of thermodynamics (see), in these conditions all systems aim at reduction of free energy.

Many biochemical synthetic reactions proceed thanks to the ekzer-gonichesky reactions managing interfaced to them E. river. At glycolysis (see), e.g., endergoniche-sky reactions of formation of ATP from ADF and phosphate are connected with ekzergo-nichesky transformation of glucose (see) in lactic acid (see). At the same time total process of glycolysis is followed by very strong reduction of free energy (A.G = — 32,4 kcal) and is almost irreversible.

See also Chemical changes. Bibliography: Glinka H. JI. General

chemistry, page 199, L., 1978;

Lenind-e r A. Biokhimiya, the lane with English, page 335, M., 1976; Stepson y. A. G. Biophysical chemistry, M., 1968.

P. L. Ivanov.