Premium
Circular dichroism of N ‐phenylnaphthylamine derivatives complexed with the β‐form of poly( L ‐lysine)
Author(s) -
Sato Yukio,
Woody Robert W.
Publication year - 1980
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1980.360191107
Subject(s) - chemistry , sulfonate , circular dichroism , steric effects , hydrogen bond , lysine , crystallography , stereochemistry , ionic bonding , hydrophobic effect , molecule , organic chemistry , amino acid , sodium , ion , biochemistry
Complex formation of 1‐anilinonaphthalene‐8‐sulfonate (ANS) and 2‐ p ‐toluidinonaphthalene‐6‐sulfonate (TNS) with the β‐form of poly( L ‐lysine) [(β‐Lys) n ] has been studied by circular dichroism (CD) and absorption spectra measurements. Not only hydrophobic interactions but also hydrogen‐bonding and electrostatic interactions contribute to complex formation. The relative importance of these stabilizing factors depends on the relative position of the arylamino group and the sulfonate. For example, ionic interactions play a significant role in the binding of 1,8‐ANS and 1,8‐TNS, but not in the case of 2,6‐TNS. The induced CD of the complexes of (β‐Lys) n with 1,8‐ANS and 1,8‐TNS is consistent with theoretical calculations for nonplanar conformations of these dyes, twisted in a left‐handed sense. As expected for steric reasons, the dominant isomer is one in which the arylamino group is oriented away from the 8‐sulfonate (α 1 ). The induced CD of complexes with 2,6‐TNS can be accounted for by an equimolar mixture of left‐handed isomers in which the arylamino group is oriented toward the 1‐position (β 2 ) and toward the 3‐position (β 1 ). Our results demonstrate that (β‐Lys) n is capable of chiral discrimination and suggest its general utility for CD studies of racemic anionic dyes.