Effect of temperature and ionic strength on the dissociation kinetics and lifetime of PNA-DNA triplexes.

Dissociation kinetics of triplexes formed by molecules of peptide nucleic acid (PNA) and DNA have been studied. The complexes consisted of oligomeric PNA containing 10 thymine bases and the dA(10) target incorporated in single-stranded (ssDNA) or double-stranded DNA (dsDNA). Their dissociation was followed by means of the gel mobility shift assay at various temperatures and sodium ion concentrations.

Investigation of the binding of Escherichia coli RNA polymerase to DNA from bacteriophages T2 and T7 by kinetic formaldehyde method and electron microscopy.

The complexes of T2 DNA with RNA polymerase of Escherichia coli were studied by two methods: kinetic formaldehyde method with preliminary fixation of complexes with low formaldehyde concentrations, and electron microscopy. For electron-microscopic investigations the effect of different conditions of formaldehyde fixation for DNA-RNA-polymerase complexes was studied and optimal fixation conditions were found. The suggested fixation method for DNA-RNA-polymerase complexes allows investigation of RNA polymerase molecule distribution on DNA in a wide range of conditions (ionic strength of the solution, weight ration of enzyme to DNA etc.

The study of DNA-RNA-polymerase complexes by kinetic formaldehyde method.

A modification of the kinetic formaldehyde method has been proposed providing a possibility for locally denatured regions (defects) formed in DNA preincubated with RNA polymerase (in the absence of nucleoside triphosphates) to be detected. This modification consists in a previous fixation of DNA-enzyme complex with small concentrations of formaldehyde, which do not induce formation of defects in DNA alone. The method has been calibrated under the conditions favourable to RNA synthesis.