![]() ![]() Yet no protein emission spectroscopy techniques are known to be applied to detecting the spectra of protein intrinsic radiation. In protein studies, IR spectroscopy is predominantly used as part of absorption spectroscopy techniques (i.e., for measuring absorption spectra). These days, IR spectroscopy has steadily been among methods for studying protein structures at the different levels of their organization. In the mid-twentieth century, first studies appeared that demonstrated the large potential of infrared (IR) spectroscopy for protein research. Being applicable to the study of protein solutions in low concentrations, the proposed approach is not only interesting from the point of view of fundamental science but also can have applied significance in biological and medical research. There is also potential for extending the available frequency range into the far infrared and terahertz ranges. At the same time, in the fingerprint region from 500 to 1,600 cm −1 (the most informative part of the infrared spectrum), the highest sensitivity of the method is demonstrated. At the sample temperature of 25°С, emission spectra can be detected in the range from 400 to 3,600 cm −1, which covers almost the entire frequency range of existing stretching and bending vibrations of molecules. Another significant advantage of the method described in the article is its noninvasiveness. It has also been demonstrated that emission spectroscopy offers advantages in the signal-to-noize ratio compared to absorption spectroscopy and allows analyzing the structural characteristics of a protein, in particular, providing information about its secondary structure. The described method allows detecting spectral lines with a radiation power of about 10 −8 W or even less. Using solution of human interferon gamma as an example, it has been shown for the first time that proteins have intrinsic radiation. The intensity of radiation is determined by the population of the respective energy states, which, according to the Boltzmann distribution, depends on temperature and frequency. Radiation occurs due to spontaneous radiative transitions from excited vibrational energy states to the ground state of molecules. It is also important to select the optimal vacuum pumping depth for the spectrometer and sample thickness. In this work, the background was a black body at the boiling point of nitrogen. The necessary conditions for detecting radiation from a sample are the use of a highly sensitive cooled detector and the presence of a cold background. Radiation is detected using a vacuum Fourier-transform infrared spectrometer, and the tested sample itself is a source of radiation. This paper describes a new method for measuring the spectra of infrared radiation emitted by protein solutions in the native state without any external excitation. 2Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia.1Institute of Cell Biophysics of the Russian Academy of Sciences, Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Pushchino, Russia.To understand that the spectral emission lines of an element have the same frequencies as the lines of the absorption spectrum.To characterize an atom by its light spectrum and to introduce spectroscopy.To distinguish between absorption spectra and emission spectra.CRC Handbook of Chemistry and Physics NSRDS-NBS 68 (1980).Ĭlick on an element to select it. Source for the values of spectral lines: CDS Strasbourg University ( link) from Reader J., and Corliss Ch.H. For this reason, a gas composed of a single atom can absorb or emit a limited number of frequencies.įor a given element, the emission spectrum (upper part of the animation) has the same frequency as its absorption spectrum (bottom part). It is "quantized" (see animation line spectrum of the hydrogen atom). One of the great discoveries of quantum mechanics is that the energy of an atom can only have certain well-defined values. The spectrum obtained can be continuous or discrete ("line spectrum"). A prism (or an array) is used to break a beam of light according to its different frequencies. ![]()
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