[Unwinding effect of F1 gene 5 protein on double-stranded polynucleotides and DNA]

The effect of gene 5 protein from bacteriophage f1 on melting of double-stranded polynucleotides and DNAs has been investigated using the UV-spectroscopy method. A dependence of the melting temperature of polynucleotide (DNA)-gene 5 protein complexes upon the polynucleotide (DNA) GC-pair content has been detected. Using experimental data and examining some model systems we came to the supposition that the lowering of melting temperature of polynucleotide (DNA) induced by this protein is probably stipulated by intercalation of the protein tyrosyl residues into one of the chains of polynucleotide (DNA) double helix.