Controlled micelle conjugation via charged peptide amphiphiles

We report the first demonstration of nonionic detergent micelle conjugation and phase separation using purpose-synthesized, peptide amphiphiles, C₁₀ -(Asp)₅ and C₁₀ -(Lys)₅ . Clustering is achieved in two different ways. Micelles containing the negatively charged peptide amphiphile C₁₀ -(Asp)₅ are conjugated (a) via a water-soluble, penta-Lys mediator or (b) to micelles containing the C₁₀ -(Lys)₅ peptide amphiphile. Both routes lead to phase separation in the form of oil-rich globules visible in the light microscope. The hydrophobic nature of these regions leads to spontaneous partitioning of hydrophobic dyes into globules that were found to be stable for weeks to months. Extension of the conjugation mechanism to micelles containing a recently discovered, light-driven proton pump King Sejong 1-2 (KS1-2) demonstrates that a membrane protein may be concentrated using peptide amphiphiles while preserving its native conformation as determined by characteristic UV absorption. The potential utility of these peptide amphiphiles for biophysical and biomedical applications is discussed.