Mode of interaction of amphiphilic α-helical peptide with phosphatidylcholines at the air-water interface

Hiromichi Nakahara, Shohei Nakamura, Takato Hiranita, Hideya Kawasaki, Sannamu Lee, Gohsuke Sugihara, Osamu Shibata

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Surface pressure (π)-, surface potential (ΔV)-, and dipole moment (μ⊥)-area (A) isotherms and morphological behavior were examined for monolayers of a newly designed 18-mer amphiphilic α-helical peptide (Hel 13-5), DPPC, and DPPC/egg-PC (1:1) and their combinations by the Wilhelmy method, ionizing electrode method, fluorescence microscopy (FM), and atomic force microscopy (AFM). The newly designed Hel 13-5 showed rapid adsorption into the air - liquid interface to form interfacial films such as a SP-B function. Regardless of the composition and constituents in their multicomponent system of DPPC/egg-PC, the collapse pressure (πc; ∼42 mN m -1) was constant, implying that Hel 13-5 with the fluid composition of egg-PC is squeezed out of Hel 13-5/DPPC/egg-PC monolayers accompanying a two- to three-dimensional phase transformation. FM showed that adding a small amount of Hel 13-5 to DPPC induced a dispersed pattern of ordered domains with a "moth-eaten" appearnce, whereas shrinkage of ordered domains in size occurred for the DPPC/egg-PC mixture with Hel 13-5. Furthermore, AFM indicated that (i) the intermediate phase was formed in pure Hel 13-5 systems between monolayer states and excluded nanoparticles, (ii) protrusions necessarily located on DPPC monolayers, and (iii) beyond the collapse pressure of Hel 13-5, Hel 13-5 was squeezed out of the system into the aqueous subphase. Furthermore, hysteresis curves of these systems nicely resemble those of the DPPC/SP-B and DPPC/SP-C mixtures reported before.

Original languageEnglish (US)
Pages (from-to)1182-1192
Number of pages11
JournalLangmuir
Volume22
Issue number3
DOIs
StatePublished - Jan 31 2006
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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