Figure 2. The effect of DSF:Cu on DNA synthesis.

Following release from thymidine block, synchronised SK-N-BE(2c) and UVW cells were exposed for 8 h to 0.3 or 0.1 μM DSF:Cu, respectively. The effect of DSF:Cu on DNA synthesis was monitored by flow cytometric analysis of propidium iodide-stained (A) or BrdU-stained (B) synchronised cells. The data are representatives of triplicate determinations. The proportions of BrdU-positive cells in G₂ are means ± SEM, n=3. Independent t-test: ^*** P<0.001. (C) The interaction between DSF:Cu and DNA was investigated by circular dichroism (CD) using treatment with ethidium bromide (EtBr) as a positive control. (D, E) The effect of DSF:Cu on the stability of the DNA molecule in response to heat treatment was investigated by CD. The absolute CD values at 245 nm (D, nadir of the negative wave) and at 275 nm (E, zenith of the positive wave) were plotted against temperature to measure change in helicity and base stacking, respectively.