[Ionic pairs in Bacillus intermedius 7P ribonuclease].

On the basis of X-ray determined coordinates specified with computer graphics and new data on amino acids sequence in the structure of Bacillus intermedius 7P ribonuclease there were analysed potentially charged residues and found ionic pairs binding independently denaturing regions-energetic domains. Five clusters of charged amino acids were found in the protein structure and several ionic bonds between the energetic domains were discovered: Asp7, Asp11-Arg109 and Lys26-Asp53,Glu72. Breaking of the latter makes their heat denaturation independent.

[A new approach to the thermodynamic role of imino acids in collagen. Solution of a thermodynamic paradox].

The dependence of denaturation transition thermodynamic parameters in various collagens from imino acid compositions has been analysed. Computational and experimental data suggest independence of the collagen molecule hydration on imino acid composition and sequence in the polypeptide chain. The continuous net of hydrogen bonds is interrupted, if imino acid residues occur in the sequence of amino acid residues, as follows from Monte Carlo computations, because the hydrogen of NH-group plays sufficient role in water shell formation for this conformation.

[Hydration of the left spiral of the poly-L-proline type. Study by the Monte Carlo method].

The paper exhibits results of hydration shell Monte Carlo calculations in poly-L-proline II and extended helix conformation and in alpha-helical and beta-structural conformations for comparison. It was found that left-handed helix of poly-L-proline II type as well as epsilon-helix are characterized by very favorable hydration. Therefore this conformation has preference as compared to other standard conformations of the main polypeptide chain.