Molecular biology in the Soviet Russia (An essay)

Stages of the evolvement and development of the major directions of molecular biology in the 1950–1980’s and its prehistory bracketing the 1920–1940’s are considered against the backgrounds of the history of the Soviet science. Short outlines of the lives and activities of the leading scientists who shaped the directions of and provided for success in studying supramolecular cell structures and molecular mechanisms of processes on a cellular level. This essay, which is far from exhaustive in describing the problems that the Soviet scientists have been dealing with, does not cover the studies of the last decade, nor does it evaluate the contributions of the living molecular biologists.     

Study of the structure of the photosynthetic reaction center of the green thermophilic bacteria Chloroflexus aurantiacus

Analysis of the Chloroflexus aurantiacus reaction centre (RC) using both protein and recombinant DNA techniques resulted in determination of its polypeptide composition and the primary structures of its two subunits. A model of the polypeptide chains' folding in the membrane is suggested based on: i) homology between L- and M-subunits of Chloroflexus aurantiacus RC and their counterparts in purple bacteria; ii) comparison of their hydropathy plots, and iii) data on the tertiary structures of purple bacteria RCs. The role of a number of functionally important amino acid residues in the RC electron transport activity is discussed. Limited proteolysis of the RC under non-denaturing conditions was used to determine the contribution of the N-terminal regions to its thermal stability.     

Monomerization of the fragment D dimer of stabilized fibrin by a secretion from the medicinal leech salivary gland]

The salivary gland secretion of the medicinal leech catalyzes the conversion into monomeric form of the fragment D dimer, the product of limited proteolysis of stabilized fibrin. Analysis of N-terminal sequences revealed identical fragments for the D-dimer gamma-gamma-chains and the D-monomer gamma-chains formed via this reaction and established the presence of only one N-terminal amino acid (Ser). These results provide evidence for the preservation of integrity of the polypeptide chains during monomerization of the D-dimer.     

Comparative study of the phospholipase activity of pathogenic and saprophytic Leptospira cultured on a serum-lecithin agar

The phospholipase activity of leptospires cultivated on serum-lecithin agar has been studied. Two zones of changes in the medium have been found to appear around the colonies of saprophytic Leptospira strains: transparent (5.25 +/- 2.09 mm wide) and turbid (6.90 +/- +/- 1.46 mm wide), which is linked with the production of phospholipases A and C. Only a single clear zone is formed around the colonies of pathogenic strains due to the production of phospholipase A. At the same time virulent Leptospira strains show greater phospholipase activity (the zones are 6.0 +/- 1.2 mm wide) than avirulent strains (the zones are 1.6 +/- +/- 0.04 mm wide).