Poly( L ‐lysine)/sulfated poly(vinyl alcohol)/acridine orange complex

In order to clarify the arrangement of sulfated poly(vinyl alcohol) (PVS) chains about the α‐helical poly(L‐lysine) (PLL) chain in the previously reported complexes of PLL/46 mole‐% sulfated poly(vinyl alcohol) (PVS‐46) and PLL/PVS‐95, induced circular dichroism was studied on PLL/PVS/acridine orange (AO) complexes in acidic aqueous solution. A positive ellipticity, [θ], of ca. 3 400 deg·cm2·dmol−1 at 465 am and small negative values of [θ] at 435 and 510 nm indicated a right‐handed super helical arrangement of AO molecules about the right‐handed α‐helix of PLL, where PVS chains were intercalated. The amount of AO molecules responsible for the induced CD was estimated as low as a few mole‐%. Taking into consideration the arrangement of ε‐amino groups of the right‐handed α‐helical PLL and the distance among the neighboring ε‐amino groups on the radial projection of the helix, the PVS chain segments could be arranged both in the right‐handed and in the left‐handed superhelices about the right‐handed α‐helix of PLL. In cases of the PLL/PVS‐25/AO and PLL/PVS‐30/AO complexes, no induced CD and a quite weak CD were obtained, resp., being consistent with random coil conformation of PLL in the PLL/PVS‐25 and PLL/PVS‐30 complexes mentioned previously.