Structure and reactivity of liposomes from phosphatidyl - nucleosides and - peptides

• Research unit: COST
• Project number: C93.0039

Key words (English)

Liposome; vesicle; phosphatidyl nucleoside; phospholipid1 nuclear meagnetic resonance

Research programs (English)

COST-Action D7 - Molecular recognition chemistry

Short description (English)

See abstract

Partners and International Organizations (English)

B, CH, CZ, D, DK, E, F, FIN, H, I, IRL, N, NL, P, S, SI, UK

Abstract (English)

Liposomes from phosphatidyl nucleosides were prepared and characterized with respect to the orientation of the lipid molecules in the liposomes and with respect to molecular interaction properties. Four different phosphatidyl nucleosides were synthesized, 5'~(1 -palmitoyl-2-oleoyl~sn-glycero-3-phospho)cytidine (POP-Cyt), 5'-(1 -palmitoyl-2-oleoyl-sn-glycero-3-phospho)inosine (POP-Ino), 5'-(1 ,2-dipalmitoyl-sn-glycero-3-phospho)cytidine (DPP-Cyt), and 5'-(1 12-dipalmitoyl-sn-glycero-3-phospho)inosine (DPP-lno). Stable liposomes with a mean diameter of about 100 nm could be prepared from POP-Cyt or from a 1:1 mixture (molar ratio) of POP-Cyt and POP-Ino. In the case of POP-Ino, the liposomes tended to aggregate. DPP-Cyt formed helical bilayers, DPP-lno formed stacked disks and partially rolled cylinders, and equimolar mixtures of DPP-Cyt and DPP-Ino formed flat disks. The liposomes of POP-Cyt and POP-Cyt/POP-Ino (1:1) were analyzed by 1 D- and 2D-1H-NMR. In the case of POP-Cyt, the presence of intermolecular interactions between H-1' of the ribose and aromatic protons of the base (H-5 and H-6) was evident from the occurrence of corresponding cross-peaks in 2D-1H-NOESY experiments. In the case of POP-CytiPOP-Ino (1:1), the same cross peaks were observed. The lack of additional cross peaks suggested that no particular interactions between the purine and the pyrimidine bases were present, which in turn suggested that the two bases were distinctly compartimentalized, possibly building patches of the same phospholipid type within a given liposome. The lack of any experimentally measurable interaction between the phosphatidyl nucleoside liposomes and complementary oligonucleotide strands were fully explained by the NMR analysis.

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C93.0039