DNA packaging in water solutions induced by polylysine and spermidine

Effect of the oligopeptide length on the DNA condensation process in aqueous-salt solutions

“…In a solution with a high ionic strength, when Na + counterions effectively screen the DNA charge, oligopeptides cannot approach the macromolecule and start interacting with the phosphate groups. At the same time, although the polycation charge is screened by the counterions in 1 M NaCl and polyelectrolyte swelling is suppressed, PLL still compacts DNA [15].…”

“…For both of them the decisive factor for DNA condensation is the condensing agent concentration in the DNA solution rather than N/P, as is observed in the DNA solutions with polycations. Moreover, polyamines also cannot condense DNA in solutions with a high ionic strength [15]. A decrease in the specific viscosity of DNA solutions with oligopeptides at certain concentrations of the latter is accompanied by a synchronous change in the optical anisotropy of the macromolecule (Fig.…”

“…There is only some decrease in the macromolecule volume, as is observed in the DNA interaction with divalent counterions [14]. It has previously been shown that in the consideration of the dependence between the specific viscosity of solutions and the concentration of components, when polylysine (PLL) is used as a condensing agent, the onset of DNA condensation is determined by the charge ratio N/P (N is the molar concentration of positively charged monomeric units of polylysine; P is the molar concentration of DNA phosphates) rather than the agent concentration [7,11,15]. The difference in the DNA interaction with LysLys and longer oligolysines can be due to that the charge of 2+ is not sufficient for effective DNA compaction.…”