The effect of oxygen on denaturation and aggregation of enzyme macromolecules during gamma-irradiation

The ribonuclease molecules irradiated in a solution in the presence of 18O2 were separated, by the method of gel-chromatography, into fractions of aggregated macromolecules, denatured monomers and the molecules which retained the original sizes. Oxygen was bound by the molecules of all fractions. The oxygen binding prevented the aggregation of macromolecules. The fractions of molecules of monomer forms, obtained after irradiation in the presence of oxygen, were more inactive than those obtained after irradiation in vacuum.     

The simultaneous synthesis of peptides and oligonucleotides on kaolinite with the participation of aminoacyladenylates

A simultaneous synthesis of peptides (2-5 residues) and oligonucleotides (3-9 residues) has been carried out on caolinite matrix using amino acids and aminoacyladenylates as substrates. The rate of oligomer synthesis on mineral surface is higher than that in solution. The mechanism of synthesis has been described. The data has been discussed in connection with abiogenesis of two major types of biopolymers, proteins and nucleic acids.     

The characteristics of the action of gamma irradiation on the secondary structure of ribonuclease in vitro and the effect of oxygen on this process]

The change in the secondary structure of ribonuclease after 60Co gamma irradiation with a dose of 1,000 Gy in 0.2% aqueous solution was estimated using the circular dichroism method. The beta structures were significantly changed, while other types of the secondary structure (alpha-helix and beta-turns) changed insignificantly. The secondary structure injury was also affected by oxygen. The data are attributed to characteristics of the secondary structure of this enzyme.