Molecular interactions between magainin 2 and model membranes in situ

Khoi Tan Nguyen, Stephanie Valerie Le Clair, Shuji Ye, Zhan Chen

Research output: Contribution to journalArticle

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Abstract

In this paper, we investigated the molecular interactions of magainin 2 with model cell membranes using sum frequency generation (SFG) vibrational spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Symmetric 1-palmitoyl-2-oleoyl-sn-glycero-3-[Phospho- rac-(1-glycerol)] (POPG) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers, which model the bacterial and mammalian cell membranes, respectively, were used in the studies. It was observed by SFG that magainin 2 orients relatively parallel to the POPG lipid bilayer surface at low solution concentrations, around 200 nM. When increasing the magainin 2 concentration to 800 nM, both SFG and ATR-FTIR results indicate that magainin 2 molecules insert into the POPG bilayer and adopt a transmembrane orientation with an angle of about 20° from the POPG bilayer normal. For the POPC bilayer, even at a much higher peptide concentration of 2.0 μM, no ATR-FTIR signal was detected. For this concentration on POPC, SFG studies indicated that magainin 2 molecules adopt an orientation nearly parallel to the bilayer surface, with an orientation angle of about 75° from the surface normal. This shows that SFG has a much better detection limit than ATR-FTIR and can therefore be applied to study interfacial molecules with a much lower surface coverage. This magainin 2 orientation study and further investigation of the lipid bilayer SFG signals support the proposed toroidal pore model for the antimicrobial activity of magainin 2.

Original languageEnglish (US)
Pages (from-to)12358-12363
Number of pages6
JournalJournal of Physical Chemistry B
Volume113
Issue number36
DOIs
StatePublished - Sep 10 2009

Fingerprint

Magainins
Molecular interactions
molecular interactions
Fourier transform infrared spectroscopy
membranes
Membranes
Lipid bilayers
Cell membranes
infrared spectroscopy
Molecules
reflectance
Phosphorylcholine
Vibrational spectroscopy
lipids
Glycerol
Peptides
molecules
inserts
glycerols
peptides

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Nguyen, Khoi Tan ; Le Clair, Stephanie Valerie ; Ye, Shuji ; Chen, Zhan. / Molecular interactions between magainin 2 and model membranes in situ. In: Journal of Physical Chemistry B. 2009 ; Vol. 113, No. 36. pp. 12358-12363.
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Molecular interactions between magainin 2 and model membranes in situ. / Nguyen, Khoi Tan; Le Clair, Stephanie Valerie; Ye, Shuji; Chen, Zhan.

In: Journal of Physical Chemistry B, Vol. 113, No. 36, 10.09.2009, p. 12358-12363.

Research output: Contribution to journalArticle

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AU - Nguyen, Khoi Tan

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