The Structural Variety of DNA-DPPC-Divalent Metal Cation Aggregates: SAXD and SANS Study

We examine the structure of aggregates formed due to DNA interaction with dipalmitoylphosphatidylcholine (DPPC) in presence of Ca2+ and Zn2+ using small-angle synchrotron X-ray diffraction (SAXD) and neutron scattering (SANS). SAXD shows structural heterogeneity as a function of the cation concentration and temperature: At low cation concentration ( 3c1mM), aggregates show two DPPC phases, one with a lateral segregation of DNA and cation, while higher cation concentration improves the DNA packing and the condensed lamellar phase is observed in DNA + DPPC + 20mMion2+ aggregates. The SANS detected the dissolution of the condensed lamellar phase into unilamellar DPPC + Zn2+ vesicles due to gel \u2192 liquid-crystal phase transition in DNA + DPPC + 20mM Zn2+ aggregates with the short fragmented salmon sperm DNA.Peer reviewed: YesNRC publication: Ye