The structural diversity of DNA-neutral phospholipids-divalent metal cations aggregates: a small-angle synchrotron X-ray diffraction study
| Autor: | Adrián Lengyel, Mária Hanulová, Sérgio S. Funari, Daniela Uhríková, Pavol Balgavý |
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| Jazyk: | angličtina |
| Rok vydání: | 2007 |
| Předmět: |
Models
Molecular Macromolecular Substances Static Electricity Biophysics Analytical chemistry Molecular Conformation Divalent Metal chemistry.chemical_compound Lamellar phase X-Ray Diffraction Phase (matter) ddc:570 Cations Lamellar structure Computer Simulation Lipid bilayer Phospholipids chemistry.chemical_classification chemistry [DNA] chemistry [Drug Carriers] Drug Carriers chemistry [Liposomes] chemistry [Macromolecular Substances] Temperature chemistry [Phospholipids] General Medicine DNA Crystallography chemistry Models Chemical Metals Dipalmitoylphosphatidylcholine visual_art X-ray crystallography Liposomes visual_art.visual_art_medium chemistry [Metals] Synchrotrons |
| Zdroj: | European biophysics journal 36, 363-375 (2007). doi:10.1007/s00249-006-0086-2 |
| DOI: | 10.1007/s00249-006-0086-2 |
| Popis: | We investigate the structure of aggregates formed due to DNA interaction with saturated neutral phosphatidylcholines [dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine] in presence of Ca(2+) and Mg(2+) cations using simultaneous synchrotron small- and wide-angle X-ray diffractions. For DPPC:DNA = 3:1 mol/base and in the range of 1-50 mM Ca(2+), the diffractograms show structural heterogeneity of aggregates. We observe the coexistence of two lamellar phases in aggregates prepared at 1 mM Ca(2+): L(x) phase with the DNA strands (of unknown organization) intercalated in water layers between adjacent lipid bilayers and L(DPPC) phase of DPPC bilayers without any divalent cations and DNA strands. Aggregates prepared in the range 2-50 mM Ca(2+) show a condensed gel lamellar phase L (g) (c) with the lipid bilayer periodicity d approximately 8.0 nm, and the DNA-DNA interhelical distance d (DNA) approximately 5.1 nm. The increase of temperature induces the decrease in the intensity and the increase in the width of the DNA related peak. In the fluid state, the condensed lamellar phase L (alpha) (c) gradually converts into L(x) phase. The aggregates do not exhibit rippled P(beta) phase. The thermal behaviour of aggregates was investigated in the range 20-80 degrees C. Applying heating-cooling cycles, the aggregates converted into energetically more favourable structure: a condensed lamellar phase L(c) (or L(x)) is preserved or we observe lateral segregation of the DNA strands and metal cations (L(x) phase) in coexistence with L(PC) phase of pure phospholipids. |
| Databáze: | OpenAIRE |
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