Differential scanning calorimetric study of the effect of intercalators and other kinds of DNA-binding drugs on the stepwise melting of plasmid DNA

Escherichia coli HU protein suppresses DNA‐gyrase‐mediated illegitimate recombination and SOS induction

“…To make a PstI site downstream of the gyrB þ gene, the Cm R SmaI fragment of pJK275 was inserted into the StuI site downstream the gyrB þ gene on pJK2033, resulting in pJK2035. pJK275 was constructed by insertion of the Km R PstI fragment of pUC4K into the PstI site of pJK273, which was obtained by insertion of the BamHI fragment containing the Cm R marker of pJL3-4779 (Maeda et al 1990) into the HincII site of pUC8 after treatment with the Klenow fragment. The BamHI-PstI fragment containing the gyrB þ gene of pJK2035 was ligated with the BamHI-PstI fragment of pUC118, resulting in pUC118-gyrB þ (Y. Kumagai, J. Kato & H. Ikeda, unpublished results).…”

The interaction of platinum complexes with DNA studied by differential scanning calorimetry.

“…So it is clear that cis-DDP binds to DNA and eases the transition of double-stranded DNA to single-stranded DNA. The decrease in the helix-coil transition temperature is more common with cis-DDP, than with other DNA-intercalating antibiotics, which cause the transition temperature to shift to higher temperature regions (12,13) . With low traps-DDP concentration, the DSC curve was similar to that for cis-DDP (Fig.…”

“…Eastman (5) has proposed that cis-DDP binds to the DNA sequences 5'-GG-3', 5'-AG-3' and 5'-GNG-3' on one strand to which the binding probability of cis-DDP is 0.65, 0.25 and 0.06, respectively. Maeda et al (11,12) showed that each peak in the DSC curve can be assigned to the particular regions of the nucleotide sequence under the helix-coil transition theory. Therefore, to know whether the binding of cis-DDP to the particular sequences affects DSC curve, the cis-DDP binding sites proposed by Eastman on one strand of pJL3-TB5 DNA were counted, and the Temperature (°C) Fig.…”

“…Frequency of the specific binding sites of cis-DDP in the individual regions contributing to the DSC peaks of pJL3-TB5 DNA. The number of the specific binding sites was scored in each of fifteen regions in pJL3-TB5 DNA contributing to DSC peaks, and the (weighted) frequency was calculated according to the formula, frequency of the binding sequences in the regions contributing to each DSC peak was plotted against the transition temperature of the corresponding regions (12). As shown in Fig.…”

“…The DSC was carried out at 0.5°C min-'. The acquisition of data from the calorimeter and all of the subsequent theoretical processing were described previously (9,10,12). RESULTS …”