From Big Medical Encyclopedia

BIOPHYSICAL CHEMISTRY (synonym: physical biochemistry, physical and chemical biology) — one of sections of biophysics studying physical and chemical bases of processes of life activity. B. x. includes studying of private questions of chemical thermodynamics, kinetics and catalysis of biological processes, physical. - chemical bases of the electric phenomena in a cell, physical. - chemical colloidal state of protoplasm, physical. - chemical mechanisms of elementary acts of reactions of biopolymers at the cellular level. The special place in B. x. it is given to studying physical. - chemical mechanisms of priming chemical changes arising in a cell at action of the ionizing radiation and also physical. - it is normal of chemical properties of separate substances and connections in a cell also at development of these or those morbid conditions.

Having arisen on a methodological basis physical chemistry (see), B. x. included elements of biological chemistry, physiology, the pathophysiology, radiology and some other medicobiological sciences studying primary mechanisms of processes of life activity in the arsenal.

B. x. it was created and was widely adopted in the fifties our century as a result of need to emphasize close interrelation physical. and the chemical phenomena in biological processes.

At B.'s sources x. in the USSR there were W. A. Engelgardt, H. M. Emanuel, A. G. Pasynsky, B. N. Tarusov. Abroad — Bulls (G. Century of Bull), Chans (V. Chance), etc.

Results of researches B. x. find the application in medicine. E.g., methods of chemical kinetics (at the description of morbid conditions and establishment physical. - the chemical mechanisms causing these morbid conditions) allowed to characterize pathological process in general, to offer physical. - chemical criteria for selection and the directed search pharmacological active drugs. At the same time there are two approaches — formal, based on a community of pharmacological properties of the drugs having relatives physical. - chemical characteristics, and the approach based on studying physical. - chemical mechanisms of a disease and selection of the means able to change physical. - chemical parameters of separate components of a cell towards their normalization. Selection of synthetic antioxidants, e.g., is based on such principle (see. Antioxidants ) for treatment of the morbid conditions which are characterized along with other indicators decrease in anti-oxidizing activity of cellular lipids. Methods B. x. allow to notice changes in an organism much earlier, than characteristic pathophysiological features of a disease appear. It is connected with the fact that physical. - chemical properties are one of the most general at the characteristic of any biological system in general and their change depends not only on change of structure or properties of separate components, but also on interference of these components at each other. So, e.g., the EPR method (see. Electronic paramagnetic resonance ) in clinical conditions it can be used for determination of level of free radicals (see. Radicals ) in blood of patients with various forms of a leukosis. On an example miyelo-and a lymphoid leukosis it is shown that the level of free radicals in leukocytes of blood of patients changes earlier, than any other symptoms of a leukosis appear (e.g., changes of quantity of leukocytes in peripheral blood), and increases in process of a course of a disease. At treatment by various chemotherapeutic drugs (Myelosanum, Dipinum, 6 Mercaptopurinum) the level of free radicals in blood decreases though in some cases does not reach the values characteristic of norm. Communication of level of free radicals in blood of patients at the time of remission with duration of remission was noted. In some cases low level of free radicals in blood at the time of remission corresponded to long remission; at the increased level of free radicals in blood time of remission was considerably reduced (K. E. Kruglyakova, Η. M. Emanuel et al., 1970).

See also Biophysics , Thermodynamics .

Bibliography: Shave D. and Whyte K. Kinetik and thermodynamics of biochemical processes, the lane with English, M., 1959; Bulls G. B. Physical biochemistry, the lane with English, M., 1949, bibliogr.; r and D.'s N R. F igoldberger. Molecular aspects of life, the lane with English, M., 1968; To l about t of c of I. Energetik of biochemical reactions, the lane with English, M., 1970; Krebs G. A. ikornberg G. JI. Energy conversions in live systems, the lane with English, M., 1959, bibliogr.; Martin R. Introduction to biophysical chemistry, the lane with English, M., 1966; Emanuel Η. M and Evseenko JI.C. Quantitative fundamentals of clinical oncology, M., 1970; Engelgardt W. A. At sources of domestic molecular biology, the Nature, No. 6, page 56, 1972; West E. S. Textbook of biophysical chemistry, N. Y. — L., 1963.

B. B. Burlakova.