[Z-form of intraphage DNA]. / Z-forma vnutrifagovoi DNK.

The bacteriophage lambda gt10 DNA containing an insertion of 20 pairs of GC-bases capable of being arranged as Z-form was cloned. Two independent methodological approaches based on the main properties of Z-form were used to study the shape of the insertion: formation of transition bridges composed of unpaired nucleotides between left-rotating Z-forms and right-rotating B-forms of helix (j-domain) and high immunogenic activity of Z-form. O-beta-diethylaminoethylhydroxyamine (OHA), an analogue of hydroxylamine, is capable of reacting specifically with unpaired cytidines. In this work this modification was used to inhibit the process of restriction at BamH1-site adjacent to (gc)10 insertion, that N-Methyl-bis(2-chloethyl) amine (MBCA) is capable of fixing the Z-form of the insertion in situ. Fixed Z-form is conserved even after DNA has been isolated from bacteriophage, thereby providing an opportunity of its identification by anti-Z-antibodies. It was shown that from 4 to 6% of the total number of insertions are in the Z-form. The hypothesis of significant role of Z-form in the process of packing of DNA molecules in capsid is put forward.

[The structural characteristics of the polyribosomes in the rat liver studied by means of a tritium label]. / Osobennosti struktury poliribosom pecheni krys, izuchennye metodom tritievoi metki.

Polyribosomes isolated from the rat liver in a medium with low ionic strength were irradiated by "hot" tritium atoms under conditions providing for the replacement of the hydrogen atoms located at the surface of polyribosomes by tritium. After fractionation of such polyribosomes, the radioactivity of the obtained fractions was measured and their proportions were calculated for the total surface accessible for the tritium atoms (in %), as well as their specific radioactivity. The material loosely associated with the polyribosomes and containing amino acyl-tRNA-synthetases is more radioactive than rRNA and r-proteins, especially concerning their specific radioactivity. This suggests that the material is organized as individual molecules located on the surface of ribosomes. The specific radioactivity of the RNA-component of this material (tRNA) is twice that of proteins, thus suggesting its surface localization in the composition of loosely associated material. Based on the pattern of labeling of rRNA and r-proteins of the native and preliminarily dissociated polyribosomes, we propose that the material, loosely associated with the polyribosomes, has affinity to both rRNA and r-proteins.

[Determination of the accessible surface of lysozyme and human serum albumin molecules by the total tritium labeling method]. / Opredelenie dostupnoi poverkhnosti molekul lizotsima i syvorotochnogo al'bumina cheloveka metodom total'noi tritievoi metki.

Amino acids composing an accessible surface of lysozyme and human serum albumin (HSA) globules were determined by the total tritium labelling method. A good correlation between our data on the distribution of the tritium label for the lysozyme molecule and X-ray data on the tertiary structure for this macromolecule was received. Lysozyme was used as a standard for determining the accessible surface of the globule albumin. It was shown that the accessible surface of the albumin globule is substantially more hydrophobic (average accessible surface area of hydrophobic amino acids is 130 A2 in HSA and 20 A2 in lysozyme) than in lysozyme. The HSA molecule is characterized by high values of: the accessible surface area, the ratio of extended area to the folded one, and the surface roughness index. These data indicate that the HSA molecule is less compactly packed than lysozyme.

[Study of the three-dimensional structure of proteins by means of tritium labeling. II. Intramolecular distribution of tritium in the N-terminal part of myoglobin and the tertiary structure of protein]. / Issledovanie prostranstvennoi struktury belkov pri pomoshchi tritievoi metki. II. Vnutrimolekuliarnoe raspredelenie tritiia v N-kontsevoi chasti mioglobina i tretichnaia struktura belka.

The possible use of the method of 3H-label introduction by means of a 3H-atom beam for investigating the three-dimensional structure (surface) of proteins was studied. The intramolecular distribution of tritium in the N-terminal part of 3H-labelled sperm-whale myoglobin was studied. The results obtained are in good agreement with the X-ray analysis data on the polypeptide chain of the protein molecule. The possible use of this method for constructing precise three-dimensional models of polypeptides and proteins is discussed.

[Study of three-dimensional structure of proteins by means of tritium labeling. I. Free amino acids as a model of residues in an unfolded polypeptide chain]. / Issledovanie prostranstvennoi struktury belkov pri pomoshchi tritievoi metki. I. Svobodnye aminokisloty kak model' ostatkov v razvernutoi polipeptidnoi tsepi.

Probabilities of the incorporation of tritium label into various amino acids with alanine as a standard have been determined by "bombing" solid targets with a 3H-atom beam (2 000 K). The results show that amino acids can be used with sufficient accuracy as models of amino acid residues in a polypeptide chain under 100%, accessibility. The resulting coefficients, if taken into consideration in the analysis of intramolecular distribution of tritium in short tryptic peptides of TMV protein, will yield an equiprobable distribution in the case when the label has been introduced into a peptide. The distribution is not uniform, however, if a labelled peptide has been isolated from an "irradiated" hydrolysate protein.