Phosphatidylserine reversibly binds Cu 2+ with extremely high affinity

Christopher F. Monson, Xiao Cong, Aaron D. Robison, Hudson P. Pace, Chunming Liu, Matthew F. Poyton, Paul S. Cremer

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

Phosphatidylserine (PS) embedded within supported lipid bilayers was found to bind Cu 2+ from solution with extraordinarily high affinity. In fact, the equilibrium dissociation constant was in the femtomolar range. The resulting complex formed in a 1:2 Cu 2+-to-PS ratio and quenches a broad spectrum of lipid-bound fluorophores in a reversible and pH-dependent fashion. At acidic pH values, the fluorophores were almost completely unquenched, while at basic pH values significant quenching (85-90%) was observed. The pH at which the transition occurred was dependent on the PS concentration and ranged from approximately pH 5 to 8. The quenching kinetics was slow at low Cu 2+ concentrations and basic pH values (up to several hours), while the unquenching reaction was orders of magnitude more rapid upon lowering the pH. This was consistent with diffusion-limited complex formation at basic pH but rapid dissociation under acidic conditions. The tight binding of Cu 2+ to PS may have physiological consequences under certain circumstances.

Original languageEnglish (US)
Pages (from-to)7773-7779
Number of pages7
JournalJournal of the American Chemical Society
Volume134
Issue number18
DOIs
StatePublished - May 9 2012

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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