Details

Autor(en) / Beteiligte

• Fukushima, Kohsuke
• Muraoka, Yoshihiro
• Inoue, Tohru
• Shimozawa, Ryosuke

Titel

Conformational study of poly( l-lysine) interacting with acidic phospholipid vesicles

Ist Teil von

• Biophysical chemistry, 1989-09, Vol.34 (1), p.83-90

Ort / Verlag

London: Elsevier B.V

Erscheinungsjahr

1989

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• Circular dichroism measurements were carried out on poly( l-lysine) in the presence of vesicles of the negatively charged phospholipids, phosphatidylserine (PS; from bovine brain), phosphatidic acid (PA; prepared from egg yolk lecithin) and dimyristoylphosphatidylglycerol (DMPG). PS vesicles induced a conformational change in poly( l-lysine) from random coil to α-helix structure in 5 mM Tes (pH 7.0), whereas PA vesicles gave rise to β-structure in the same buffer. The fraction of α-helix, F α (or β-structure, F β), increased with increasing PS (or PA) concentration, reaching a saturation value of about 0.7 (or about 1). Mixed vesicles comprising PS and dilauroylphosphatidylcholine (DLPC) also induced α-helix conformation, however, the saturation value of Fα diminished with decreasing PS content in mixed vesicles. On the other hand, the spectral patterns for poly( l-lysine) in DMPG vesicle suspensions exhibited the coexistence of α-helix and β-structure. Both F α and F β increased with DMPG concentration and reached saturation values of about 0.5. Mixed vesicles composed of DMPG and dimyristoylphosphatidylcholine (DMPC) led to a reduction in F β, while F α remained almost constant. The diversity in ordered structure induced by different phospholipid vesicles suggests the participation of lipid head groups in determining the secondary structure Of poly( l-lysine) adsorbed on the vesicular surface.