Formation and stability of helical poly (N ϵ , N ϵ , N ϵ ‐trimethyl‐ L ‐lysine) in sodium perchlorate solution

Poly(trimethyl‐L‐lysine), [Lys(Me 3 )] n , is converted from random coil to α‐helix at about 1/30 of the NaClO 4 concentration required by poly(L‐lysine), (Lys) n . NaClO 4 generates turbidity in [Lys(Me) 3 ] n at concentrations above that required for helix formation, and decreases turbidity above l M NaClO 4 . The turbidity runs parallel to enhanced, and then decreased, fluorescence of a dansyl label. Helix formation per se does not induce enhanced fluorescence. Increasing NaClO 4 concentration increases T m linearly with log[NaClO 4 ] for both (Lys) n and [Lys(Me 3 )] n until the denaturing effect of high NaClO 4 sets in. Increasing NaClO 4 also increases the breadth of the transition. Heating helical [Lys(Me 3 )] n or (Lys) n does not produce a CD spectrum resembling that of “random‐coil” (Lys) n , except for [Lys(Me 3 )] n at relatively low NaClO 4 concentration.