BIOCHEMILUMINESCENCE

From Big Medical Encyclopedia

BIOCHEMILUMINESCENCE (Greek bios life + chemeia chemistry + a luminescence) — the luminescence of live organisms, and also their separate bodies and fabrics arising due to energy of the exothermic chemical (biochemical) reactions proceeding in them. Being a special case luminescences (see), B. is subdivided into a bioluminescence and a superweak luminescence.

A bioluminescence — the luminescence inherent seen by an eye a nek-eye to live organisms which is let out by usually specialized systems and characterized by high performance of transformation of chemical energy to the public (e.g., a luminescence of svetlyak, the luminescence of the sea or punks caused by life activity of microorganisms, etc.).

The superweak luminescence is peculiar, obviously, to all live organisms; it accompanies a number of processes, hl. obr. oxidizing, proceeding in normally functioning live organism, in cells or in separate cellular fragments. The main objects on which the phenomenon of a superweak luminescence was for the first time revealed and which luminescence is studied most in detail are roots of cereal and bean plants, leaves of the higher plants, and also tissue of a liver of mice and rats.

Unlike a bioluminescence, the superweak luminescence is characterized by rather low performance of transformation of chemical energy to the public and can be registered only by means of highly sensitive optical devices. Variety of types of the chemical transformations causing a bioluminescence, distinctions in intensity, spectral structure and temporary characteristics of a luminescence the existing ideas of random distribution of a bioluminescence among various representatives of the live world and about lack of the uniform evolutionary line of the shining organisms confirm.

Intensity of a luminescence of live organisms can be very considerable. The luminescence of svetlyak differs in the greatest intensity; e.g., at a svetlyak of Photinus pyralis intensity of a luminescence at the beginning of flash corresponds 0,02 St. Distinctions in spectral structure clearly are visible by comparison of a luminescence of a svetlyak, radiation to-rogo has a maximum at 565 nanometers, with a luminescence of bacteria which maximum of radiation lies within 470 — 500 nanometers, or the crustaceans who are letting out light in a blue spectral range. Duration of a luminescence of various organisms also varies (from long, proceeding the whole hours, rather constant luminescence, before short flashes which duration at some svetlyak is measured by fractions of a second).

At the majority of live organisms the luminescence lets out either all body of an organism or its specialized bodies. Also organisms (e.g., a crustacean Cypridina hilgendortii) which luminescence arises owing to release of special substances in external environment are described.

The phenomenon of a superweak luminescence was revealed only in 20 century and is intensively studied only in the last 10 — 15 years. By the nature superweak luminescences divide on:

1) mitogenetic radiations;

2) the luminescences arising at the back photochemical reactions;

3) the superweak spontaneous luminescences accompanying dark processes in cells and fabrics.

Mitogenetic radiation was revealed in 1923 A. G. Gurvich. This radiation in short ultra-violet area, extremely low intensity which is let out vegetable and zooblasts. Radiation was registered by means of the biological detector, in quality to-rogo applied cultures of yeast and a cell of roots of onions. Originally mitogenetic radiation attracted great interest since there was a hope to obtain new information on the exchange processes proceeding in a normal cell with their help; attempts to use mitogenetic radiation for diagnosis of cancer became. However the biological detector, with the help to-rogo registration of radiation was made, it was imperfect, demanded great individual skills and did not guarantee against possible mistakes. Attempts to find radiation by means of any physical. methods were unsuccessful; it was also not succeeded to simulate mitogenetic radiation by means of physical. sources of an ultraviolet light. All this served as the reason of mistrust of many researchers to the fact of existence of mitogenic beams and led practically to full suspension of similar researches.

Luminescences at the back photochemical reactions — the weak, fading in time luminescences; are let out by green parts of plants after their preliminary lighting by visible light. The range of this luminescence is close to a range of fluorescence of a chlorophyll, and the action spectrum is similar to an action spectrum of photosynthesis. The form of a curve of decay of luminescence has difficult multicomponent character, changes depending on intensity and spectral composition of the operating light, time of lighting, temperature and can be not always described mathematically. The physiological condition of photosynthesizing organisms also has significant effect on intensity and a form of a curve of attenuation of afterglow. Afterglow has a temperature optimum (e.g., at leaves of haricot at t ° 27 — 30 °). At increase and fall of temperature there is a change of a form of a kinetic curve of attenuation and decrease in intensity of a luminescence. Weak afterglow of a leaf is found also at a temperature of liquid nitrogen (— 170 °).

A superweak spontaneous luminescence of vegetable and animal fabrics — radiations of extremely low intensity (10 — 100 quanta in 1 sec. on 1 cm 2 ) with a maximum in a visible part of a range; it is observed in the presence of oxygen of air, increases with temperature increase.

Plants have a temperature maximum of a luminescence at t ° 37 — 42 °, situation to-rogo matches the moment of the beginning of death of a plant. At heat-resistant organisms this maximum lies at more high temperatures. Increase of intensity of a luminescence is registered also at decrease in temperature, at the time of «cold death» of fabrics (this flash of intensity of a luminescence at frost-resistant plants is shown at rather lower temperatures). In normal conditions the luminescence keeps at a low level. Death of an organism is followed by emergence of the «destructive» luminescence which is intensively developing in time.

The major factors strengthening a superweak luminescence — ionizing radiation, ions of metals of variable valency, hydrogen peroxide, some chemical carcinogens (e.g., derivatives of anthracene, etc.). Antioxidants (see), and also cyanides etc. lead the connections connecting ions of metals of variable valency to decrease in level of a superweak luminescence.

Not only whole fabrics, their homogenates and extracts, but also separate cellular fractions are capable to let out a superweak luminescence (mitochondrions, microsomes). As a rule, the luminescence of the unimpaired fabrics differs in the lowest intensity. The luminescence of lipid fractions, and also the substrates enriched with lipids differs in rather high intensity. Fractions, free of lipids, practically do not let out a luminescence. Cellular organellas in suspensions with difficulty change intensity of a superweak luminescence depending on the functional condition and action of external factors.

Superweak spontaneous luminescences managed to be found only after creation and implementation in biological researches of highly sensitive quiet detectors of low light flows — photo multipliers (see). In the beginning radiation from roots of sprouts of the higher plants was registered. Weaker luminescence of fabrics of animal organisms managed to be registered only in 1961.

Methods of a research of biochemiluminescence. The main specifics of the researches connected with studying of biochemiluminescence consist in need of quantitative registration of intensity and spectral structure of low light flows. In this regard visual registration of a superweak luminescence becomes impossible especially as an eye has some more the features which are sharply limiting possibilities of its use: subjectivity, long adaptation, narrow area of spectral response (400 — 750 nanometers), inconstancy of provision of a maximum and rather low sensitivity of color sight.

Photographic methods of registration were also not widely adopted hl. obr. owing to complexity of quantitative processing of results.

The greatest distribution was gained by physical methods of registration B. These methods are based on use of the phenomenon of photoeffect in combination with various electronic methods of strengthening of a signal. Many of photo multipliers possess a high intensification coefficient (about 10 5 — 10 9 ). For registration of a superweak spontaneous luminescence of fabrics use the photo multipliers which are specially selected on the minimum tempo noise and the maximum integral sensitivity (e.g., the FEU-42 type). Introduction of the scheme of integration at the exit allows to carry out continuous record of a signal on a tape of the recorder.

The choice of methods of measurement of spectral structure of a luminescence is defined by intensity of a light flow. A range of a bioluminescence — luminescences of rather high intensity — study by means of high-aperture monochromators and spectrographs. At registration of superweak luminescences approximate assessment of a range (because of considerable weakening of a light flow at the exit of the monochromator) is received by means of interferential light filters or a set of stained glasses with sharp borders of a transmission («boundary light filters»).

The kinetics and spectral structure of luminescences at the back photochemical reactions are studied on the devices allowing to carry out registration of afterglow later a controlled time slice upon termination of effect of light.

Mechanisms of the processes leading to emergence of a bioluminescence, owing to their variety and complexity are studied not enough (the main components of the system responsible for emission of light are installed the general patterns of the processes proceeding at the same time etc. are found out).

At considerable number of types the bioluminescence arises owing to processes of enzymic oxidation of the special substances called by luciferins. The enzymes catalyzing oxidation of luciferins carry the name luciterases (see). As a rule, they differ in extremely high photon yield of a luminescence. For normal functioning luciferin-lyutsiferaznoy of system is required usually availability of oxygen, ATP, ions of metals of variable valency etc. Luciferins and luciterases at various species are not identical, also the structure of additional components of this system is not identical, mechanisms of the processes leading to emergence electronically of the excited particles differ markedly. Besides, it is established that in certain cases the bioluminescence is not connected about luciferin-lyutsiferaznoy by reaction. E.g., the luminescence of a jellyfish of Aequorea arises at interaction of specific protein (ekvarin) with ions of Ca 2+ , and in this process light is let out for lack of oxygen.

The luminescence at the back photochemical reactions arises in oxidation reactions by oxygen of air primary got into condition a chlorophyll (radical ion). For afterglow responsibly several independent reactions. The fact that the curve of attenuation of afterglow of photosynthesizing organisms consists at least of three components differing in different temporary characteristics and sensitivity to effect of inhibitors demonstrates to it. In the turning green leaves long afterglow is connected with accumulation of the aggregated forms of a chlorophyll-a, then a chlorophyll-b in the beginning.

Superweak spontaneous luminescences arise owing to the autookislitelny processes proceeding in fabric lipids. Connections of the lipidic nature, especially unsaturated remains of fatty acids and phospholipids, are most sensitive to oxidation by molecular oxygen. High tendency of these connections to an autookisleniye, and also their prevalence among live organisms explains extremely wide spread occurance of the phenomenon of a superweak spontaneous luminescence.

Origins of a luminescence are explained by the theory of free radical chain liquid-phase oxidation. According to this theory free radicals (see), the oxidations conducting a chain (usually it is peroxide radicals), can react interactions with each other (a recombination or disproportionation). There is a break of two chains of oxidation, formation of reaction products in a molecular form and energy release (about 100 kcal/mol), sufficient for excitement of a luminescence in a visible part of a range. Intensity of the luminescence arising at a recombination of free radicals is proportional to a square of their concentration in system.

It is necessary to consider, however, that not all energy which is released at a recombination of free radicals goes for formation of light. The probability of this process is very small, about one quantum on 108 — 1212 acts of a recombination, than and extremely low intensity of superweak spontaneous luminescences speaks.

Mechanisms of the processes leading to emergence of a superweak spontaneous luminescence are not limited only to reactions of auto-oxidation of lipids. In literature there are data indicating communication of a luminescence with processes of formation of peroxides of fatty acids (from the unsaturated fatty acids activated by coenzyme A) which are formed as one of chain links of β-oxidation fat to - t; some data speak also about communication of a luminescence of vegetable organisms with activity of an askorbinoksidaza and the self-oxidized flavoproteins and some (there is not enough still concretized) specific biochemical reactions.

The luminescences radiated by biological organisms, probably, do not play any role in power of a live organism. The direct biological role and value of these luminescences in general also remain not clear. It is undoubted, however, that B. will play an important role in understanding of mechanisms and ways of regulation of composite biochemical reactions, and also will help to understand molecular mechanisms of generation of light at the final stages of these reactions.

If the biological role of B. continues to cause a controversy, then its value (hl. obr. superweak spontaneous luminescences) in medicine and agriculture it is rather big already now. It is defined first of all by that information, to-ruyu bear these luminescences, about the thin and very important biological responses proceeding in an organism as is normal, and at a number of pathological processes.

Applied value a luminescence appeared as if in inversely proportional dependence on its intensity. So, nearly the only practical use of a bioluminescence is the possibility of definition of ATP in complex biological substrates.

On the contrary, superweak spontaneous luminescences are used extremely widely in various branches of science and practicians. Practical value of superweak spontaneous chemiluminescence is based that with its help it is easy to register the level of radical non-enzymatic oxidation reaction in lipids and phospholipids of cell membranes, and also to establish transition of these reactions from the stationary level characterizing a normality

to the non-stationary mode of an autouskoreniye (see. Thermodynamics ), This transition is a critical stage in defeat of a cell. Lack of specificity in the above-stated mechanism of defeat allows to use superweak spontaneous chemiluminescence for assessment of the damaging action of many adverse and toxic factors, and also for definition of resistance of specific biologic forms to these or those adverse external effects. Rapid tests of definition of degree of resistance of plants to temperature, osmotic and toxic influences, definitions of optimal conditions of adaptation, and also extent of tempering of plants are developed.

The superweak luminescence changes in a characteristic way at a number of pathological processes and infectious diseases of animals and the person (radiation defeat, cancer, tuberculosis, avitaminosis, etc.). These changes allow to characterize process, and also to define efficiency of action of therapeutic agents; studying of dynamics of a superweak luminescence allows to estimate degree of suitability of tinned fabrics for transplantation etc.


Bibliography: Bioluminescence, under the editorship of A. I. Zhuravlev, M., 1965; Vladimirov Yu. A. Superweak luminescences at biochemical reactions, M., 1966, bibliogr.; Vladimirov Yu. A. and Archakov A. I. Peroxide oxidation of lipids in biological membranes, M., 1972, bibliogr.; Tarusov B. N. Superweak luminescence of live organisms, M., 1972; Tarusov B. N., Ivanov I. I. and P e of t r at with e in and the p Yu. M. Superweak luminescence of biological systems, M., 1967, bibliogr.

I. I. Ivanov.

Яндекс.Метрика