ABSTRACT
The study of intermolecular forces in bioorganic molecular complexes is necessary for understanding of functioning mechanisms of the living matter on the molecular level. One of promising experimental methods in such studies is low-temperature vibration spectroscopy of these molecular complexes in matrices of frozen inert gases. The method permits to study both isolated molecules and their small complexes (dimers, trimers, and so on) under unique conditions being characterized with the combination of advantages of the solid phase of the sample, the objects studied, and under weak influence of the medium surrounding (the matrix). Besides the description of the approach for estimation of a number of hydrogen-bonded molecular complexes formed in the matrix, the analysis of their spectral characteristics, some technical and methodological peculiarities of the matrix isolation of hydrogen-bonded complexes are described in the overview.
8.1 IntroductionThe study of properties of nucleic acids in order to understand mechanisms of genetic information storage and the genome transcription/replication function on the molecular level is one the direction of molecular biophysics that is actively elaborated in the past decade. An understanding of these mechanisms is very important because all biological information necessary for reproduction of new living cells from the bioorganic compounds is stored by means of these biopolymers. At the same time, all nucleic acid bases (“letters” by the help of which this information has been recorded), both canonic and minor ones, are derivatives of only two compounds: purine and pyrimidine. Why are, from the greatest variety of organic compounds, just these two compounds assumed as the basis of the genetic code? Most probably, the answer to this question has to be looked for in peculiarities of intermolecular interactions of these molecules with each other and with other biomolecules. It can be supposed that some essential peculiarities of intermolecular interactions of nucleic acid bases are common for many organic or biological molecules. Thus, on the one hand, revelation of these common properties and fine features of intermolecular interactions of nucleic bases is very important for genome function, on the other hand, the results of these investigations can have influence essentially on solving many other biophysical problems, including a question of the life origin, drug design and so on. Studies in the framework of this problem decision are carried out both on the native DNA and on model objects starting from nucleic acid bases and/or from various synthetic polymers and oligonucleotides. To gain a better understanding of the role of various chemical functional groups in the intermolecular interaction, the modified nucleic acid bases or simplest derivatives of purine and pyrimidine are often used.It should be noted that majority of experimental methods does not provide direct information on intermolecular interactions. Therefore, for the interpretation of the experimental (spectroscopic, for example) data in the terms of the structure and the energy of molecular complexes, the combination of the experiment and of the well-developed theory is required. Thus, at present, the main problem in the intermolecular interaction study is to find or create the corresponding theoretical model, which explains or better
