Nucleic acids investigation In the early 1930s, A. N. Belozersky was the first in the USSR to begin a systematic study of
nucleic acids. At that time, two types of nucleic acids were known: thymonucleic (
DNA) isolated from calf thymus and "yeast" (
RNA) found in yeast and wheat seedlings. The first was called "animal," and the second was called "vegetable." The first significant works performed by A. N. Belozersky relate to the issue of "animal" and "plant" nucleic acids. In 1934, articles by A. R. Kiesel and A. N. Belozersky appeared in the journal "
Hoppe-Seyler's Zeitschrift für Physiologische Chemie" and then in 1935 in the "Scientific Notes of Moscow State University''. In these articles, the presence of thymonucleic acid in plant cells was shown. A. N. Belozersky was the first to isolate and identify
thymine, first from the seedlings of pea seeds and then from the seeds of other legumes. He isolated the
DNA itself from
horse chestnut seeds. Subsequently, the presence of
RNA and
DNA was confirmed in linden buds, onion bulbs, and wheat germ. The results obtained by Belozersky made it possible to reject the division of nucleic acids into "animal" and "plant" and to affirm the idea of the universal distribution of
DNA in both plant and animal cells. While Belozersky was studying bacteria, he noted the high content of nucleic acids in cells, amounting to 30% of the dry weight, unlike higher organisms. A. N. Belozersky concluded that this fact is associated with high rates of reproduction and growth of bacteria. Later, A. N. Belozersky showed that the amount of nucleic acids, especially
RNA, is not a constant value for one species and changes with the age of the culture: young bacterial cells may contain more
RNA than old ones. Andrey Nikolaevich pointed out a new aspect (at the same time with
T. Caspersson and
J. Brachet): the relationship of the number of nucleic acids with the intensity of protein biosynthesis. These conclusions were made by A. N. Belozersky long before the appearance of the "molecular biology" term associated with the publication in the journal "
Nature" by James
J. Watson and
F. Crick on the establishment of a spatial model of the
DNA molecule. Thus, as a result of research from 1939 to 1947, A. N. Belozersky obtained the first scientific information in the world on the content of nucleic acids in various bacterial species. In a paper published in 1957 in Russian, and in 1958 in English, A. N. Belozersky and his student A. S. Spirin discovered an inconsistency between the composition of
DNA and
ribosomal RNA. They noticed that, with a wide range of
DNA changes, the composition of
RNA varies little from species to species. At the same time, the composition of proteins also varies greatly from species to species. Soviet scientists have proved that the DNA-RNA-protein biosynthesis scheme requires that all elements be in a certain composite correspondence. This conclusion led to the destruction for the old scheme of this process.
F. Crick wrote about the article by Belozersky and Spirin: “The phase of confusion was started by an article by Belozersky and Spirin in 1958. The data they provided showed that our ideas on a number of important points were too simplistic.” Soviet scientists discovered that there is a certain part of
RNA in the cells that coincides in composition with
DNA and is determined by its structure. Later, they suggested that this part of
RNA is a link in the transmission of genetic information from
DNA to proteins. Part of the
RNA discovered by Belozersky and Spirin turned out to be a rapidly synthesizing form of
RNA that transfers genetic information from
DNA to ribosomes. Later, this part of the
RNA was called messenger RNA (
mRNA).The work on the study of the nucleotide composition of
DNA and
RNA in bacteria was the beginning of numerous studies of the composition of nucleic acids in other organisms. These studies were conducted from 1958 to 1965 in groups of the Moscow State University and the USSR Academy of Sciences, headed by A. N. Belozersky. As a result, the composition of DNA and RNA was studied in many actinomycetes (N. V. Shugaeva), fungi (B. F. Vanyushin), algae (M. V. Pakhomova, G. P. Serenkov), and some higher plants (B. F. Vanyushin). A. N. Belozersky actively participated in the creation of modern genosystematics (DNA systematics,
DNA taxonomy). Today, this direction is being developed by A. S. Antonov and other students of Belozersky.The scientific activities of the groups headed by A. N. Belozersky include the study of the species functional specificity of adaptive RNAs (G. N. Zaitseva), the study of changes in the
amino acid composition of proteins in response to the substitution of nucleotides in DNA (A. S. Antonov), and the study of phosphate in the simplest organisms, particularly in aspects of its transfer from the environment, transport, accumulation, and forms of existence (I. S. Kulaev, M. S. Kritsky).
Antibiotics Another object of A. N. Belozersky's research was
antibiotics, the study of which he began during
World War II. A. N. Belozersky studied the chemical structure of one of the most effective Soviet antibiotics,
gramicidin S, first obtained by
G. F. Gause and his wife M. G. Brazhnikova. In the first works on this topic, the polypeptide nature of gramicidin was shown and its amino acid composition was determined (A. N. Belozersky, T. S. Paskhina). Furthermore, several substituted gramicidin derivatives were obtained, and their activity was studied. These works were carried out in the newly organized laboratory of antibiotics at the .
Structure of proteins and their complexes with nucleic acids A. N. Belozersky was interested in the question of the existence of complexes between nucleic acids and proteins (called "
nucleoproteins") in
in vivo systems. He made an attempt to fractionate nucleoprotein samples and thus developed a methodological scheme for this process, which later played a major role in the study of nucleic acids. Based on his experiments, Belozersky concluded that nucleic acids in cells exist in various complexes with proteins: unbound, labile, and firmly bound. It was assumed by F. Mischer and A. Kossel that the protein component of nucleoproteins is
histone, a protein that doesn't contain
tryptophan. The research of A. N. Belozersky in 1936–1942 established for the first time the presence of tryptophan-containing proteins in the nucleoproteins of plants and animals. Also, A. N. Belozersky and
G. I. Abelev isolated histones from wheat germ deoxyribonucleoprotein. This was another proof of the unity of the principles of the organization of the nuclear apparatus in plants and animals.
Other areas of research The study of the DNA nucleotide composition in different organisms led to another direction – the study of
methylated purine and
pyrimidine bases in DNA. These studies were carried out by a student of A. N. Belozersky, B. F. Vanyushin. A. N. Belozersky made a great contribution to the research on inorganic
polyphosphates and
teichoic acids. At the Department of Plant Biochemistry, V. B. Korchagin (1954) and I. S. Kulaev (1957) wrote the first PhD dissertations on polyphosphates. I.B. Naumova (1903–2003), a graduate of the Department of Plant Biochemistry, studied the structure and functions of teichoic acids. During his years at the N. F. Gamalei Institute of Epidemiology and Microbiology of the USSR Academy of Medical Sciences, A. N. Belozersky conducted studies of the antigenic and immunogenic properties of E. coli nucleoproteins. Under his leadership, studies of polysaccharides were initiated in different groups of microorganisms: algae, azobacteria, and
actinomycetes. A wide variety of chemical structures of cell wall
polysaccharides were found. == Awards and scientific recognition ==