Charged poly (L-lysine) forms a random coil in water (pH 7) and an a-helix in methanol. Cyanine (NK-2012) dyes combine with these charged poly(L-lysine)s to produce S-chiral and R-chiral dimers in water and methanol, respectively. The dimers on the a-helix show a circular dichroism strength (with a single Davydov splitting) 10 times greater than on the random coil (with several circular dichroism bands). These results indicate that the binding state of NK-2012 dyes is remarkably dependent on the secondary structure of poly(L-lysine) and the a-helix provides a single binding mode for the dyes.
Посилання на статтю:
Unique property of cyanine dyes on charged poly(L-lysine) / Masaaki Shibata, Hirotaka Ihara* and Chuichi Hirayama // Polymer. – 1993. – Vol 34. – P. 1106-1108.