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Title: Calcium and zinc differentially affect the structure of lipid membranes

Interactions of calcium (Ca 2+) and zinc (Zn 2+) cations with biomimetic membranes made of dipalmitoylphosphatidylcholine (DPPC) were studied by small angle neutron diffraction (SAND). Experiments show that the structure of these lipid bilayers is differentially affected by the two divalent cations. Initially, both Ca 2+ and Zn 2+ cause DPPC bilayers to thicken, while further increases in Ca 2+ concentration result in the bilayer thinning, eventually reverting to having the same thickness as pure DPPC. The binding of Zn 2+, on the other hand, causes the bilayers to swell to a maximum thickness, and the addition of more Zn 2+ does not result in a further thickening of the membrane. Agreement between our results obtained using oriented planar membranes and those from vesicular samples implies that the effect of cations on bilayer thickness is the result of electrostatic interactions, rather than geometrical constraints due to bilayer curvature. This notion is further reinforced by MD simulations. Lastly, the radial distribution functions reveal a strong interaction between Ca 2+ and the phosphate oxygens, while Zn 2+ shows a much weaker binding specificity.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Comenius Univ. in Bratislava, Bratislava (Slovakia); Joint Institute for Nuclear Research, Dubna - Moscow Region (Russia)
  2. Joint Institute for Nuclear Research, Dubna - Moscow Region (Russia)
  3. Joint Institute for Nuclear Research, Dubna - Moscow Region (Russia); Dubna State Univ., Dubna - Moscow Region (Russia)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  5. Comenius Univ. in Bratislava, Bratislava (Slovakia)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 33; Journal Issue: 12; Journal ID: ISSN 0743-7463
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 59 BASIC BIOLOGICAL SCIENCES
OSTI Identifier:
1351793