Protein radiometers

Krasnoyarsk scientists have proposed using glowing proteins to detect radiation

"Open Science" Egor Zadereev, Federal Research Center of the KNC SB RAS

Scientists of the Krasnoyarsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences, together with colleagues from several Russian universities, proposed using luminous proteins to test low-dose radioactive effects. In experiments with tritium water, they showed that the glow color of the discharged obelin protein changes even at low radiation doses, which opens up the possibility for creating new systems for testing radiation toxicity. The results of the study are published in the journal Analytical and Bioanalytical Chemistry (Alieva, Kudryasheva, Variability of fluorescence spectrum of coelenteramide-containing proteins as a basis for toxicity monitoring).

Many organisms in nature glow. If for the layman all types of glow are similar, then from the point of view of science there are fundamental differences between them. For example, the so–called living glow - bioluminescence – is determined by chemical reactions involving biological catalysts of a protein nature. As a result of these reactions, an excited molecule is formed that emits visible light. In addition to the "chemical" method of pumping fluorescent molecules with energy, there is another – their direct excitation when irradiated with light.

The most famous luminous biomolecule is the famous green fluorescent protein (GFP – green fluorescent protein), which emits light in the green region of the spectrum when irradiated with blue light. For the research of this protein, a group of American scientists received the Nobel Prize in Chemistry in 2008. Since then, there has been a boom in the study of luminous biomolecules. Such proteins are isolated from various organisms. They find their application primarily in test systems. Scientists change the color of the glow of these molecules; introduce genes responsible for the synthesis of radiating proteins into other organisms; create systems for medical diagnostics, visualization of intracellular processes, detection of pollutants in the environment.

In a recent study, Krasnoyarsk biophysicists drew attention to another type of fluorescent proteins – discharged photoproteins – and proposed using them for biotesting radioactive effects. Earlier, Krasnoyarsk scientists investigated the glow system of the marine polyp Obelia longissimi and isolated the luminous protein obelin. After the bioluminescent reaction, a "discharged" obelin (a complex protein complex) is formed, which has fluorescent properties. If you shine a light on this complex, then in the dark it will emit light in a wide range – from purple to blue-green. It turned out that the discharged obelin is a convenient object for biotesting various toxic effects, in particular, radiation exposure. As a source of low-dose radiation, scientists used a beta-emitting isotope of tritium in the composition of tritium water. When the discharged obelin was irradiated with even small doses of beta radiation, the contributions of violet and blue-green colors in the spectrum of the molecule's luminescence changed.

Changing the luminescence spectrum of a discharged obelin molecule
under the influence of radioactive radiation.

"Now the development of biotests of different levels is relevant. In this way, all manifestations of toxicity can be investigated – from integral effects on the body to changes at the level of elementary physico-chemical processes that occur in biological molecules. In our case, the radioactive effect affects the structure of the protein complex. That is why the color of its glow changes. As a result, we are not only getting a new biotest, but also getting closer to understanding the mechanisms of toxicity," says a leading researcher at the Institute of Biophysics, FITC KNC SB RAS, Professor at Siberian Federal University, Doctor of Physical and Mathematical Sciences Nadezhda Kudryasheva.

In fact, any molecule, when examined in detail, is a complex mechanism, for the operation of which the interaction of its fragments is important. Thus, the intensity of the glow of a discharged obelin in the violet and blue-green parts of the spectrum depends on the spatial structure of the molecule and the efficiency of the transfer of an elementary particle – a proton – inside the protein complex when excited by light. Any violation of the structure of this protein leads to a decrease in the efficiency of proton transfer and an increase in the contribution of the violet component in the luminescence spectrum. It turns out that scientists have reached the basic level of radiation exposure to the molecule – its spatial configuration changes under the influence of radiation.

"We found that changes in the color ratio in the radiation spectrum of such fluorescent biocomplexes are typical not only for radiation. Just the other day, we published an article describing similar reactions for a variety of negative effects – organic compounds, radiation, temperature changes. We are talking about a new physico-chemical approach to toxicity testing. We are reaching the basic level of testing with the help of a simple system that evaluates the effect of a toxicant on the structure of a biological macromolecule. At the same time, it is possible to judge the change of a molecule by its fluorescence, i.e. by a convenient and widely used method, unlike standard structural analyses, which often involve complex, expensive and destructive sample preparation. Such systems can be very sensitive, miniature and relatively cheap," explains Nadezhda Kudryasheva.

Portal "Eternal youth" http://vechnayamolodost.ru  09.06.2017