[Specificity of binding of regulatory proteins with DNA: possible explanation in terms of "point" interactions].

On the basis of the previously obtained data on the specificity of the interactions between amino acids and nucleotide bases an attempt is undertaken to explain the origin of the specificity of binding of repressors and cro proteins to corresponding operator DNA sequences in phages lambda and P22. The rules describing the interactions between amino acids and bases are supposed to be the same for the binding of different proteins to DNA. The suggested consideration, based on the known crystallographic data as well, allows to describe the specific binding of studied regulatory proteins to operators, the absence of their binding to other DNA sequences and the decrease of their affinity to the operator sites due to the mutations.

[Study of specific interactions of amino acid esters with the synthetic polynucleotides poly(A) x 2 poly(U), poly(A) x poly(U) and poly(A) by thermal denaturation].

The interactions of amino acid esters with poly(A)x2poly(U) and poly(A)xpoly(U) have been investigated by means of thermal denaturation of these polynucleotides. The esters under consideration raised the melting point, revealing the preferable binding to helical polynucleotide structures. The melting point shifts demonstrate the following sequence of the stabilities of these complexes: Arg greater than Lys much greater than His greater than Met greater than Ser greater than Gly.

[Spectroscopic study of interactions between nucleic acid bases and amino acid esters in dimethylsulfoxide].

Interactions between nucleic acid bases (A, T, U. C) and some amino acid esters have been investigated by IR and UV spectroscopies in dimethylsulfoxide. The stability of associates of amino acid esters with the bases was established to form the following sequence: C greater than A much greater than U, T.