SELECTIVE H-DEPENDENT RELEASE OF CONTENTS FROM THYMINE-LABELED PHOSPHOLIPID-VESICLES BY AN ADENINE-LABELED POLYELECTROLYTE()

Copolymers bearing 5.6, 9, or 11.7 mol % of adenine residues were prep ared by radical copolymerization of 2-ethylacrylic acid (EAA) and 9-[[ 2-(methacryloyloxy)ethoxy]methyl]adenine (MAAd). A double-chain surfac tant with thymine in the headgroup was synthesized and used in mixture s with egg yolk phosphatidylcholine (EYPC) to prepare thymine-labeled unilamellar lipid vesicles. Analysis of the pH-dependent behavior of t he copolymers revealed that release of contents could be effected from labeled vesicles in competitive experiments in which unlabeled vesicl es remained intact. Selectivity was greatest for the 9 mol % copolymer and was reduced at either lower or higher levels of adenine labeling. The selective recognition of the labeled membranes is ascribed to int eractions between polymer-bound adenine and surface-bound thymine func tional groups.