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artículo con referato
"Molecular Insight into the Line Tension of Bilayer Membranes Containing Hybrid Polyunsaturated Lipids"
Carla M. Rosetti, Guillermo G. Montich and Claudio Pastorino
J. Phys. Chem. B 121(7) (2017) 1587-1600
Line tension (γ) is a key parameter for the structure and dynamics of membrane domains. It was proposed that hybrid lipids, with mixed saturated and unsaturated acyl chains, participate in the relaxation of γ through different mechanisms. In this work, we used molecular dynamics simulations of the coarse-grained MARTINI model to measure γ in liquid-ordered–liquid-disordered (Lo–Ld) membranes, with increasingly larger relative proportion of the hybrid polyunsaturated lipid PAPC (4:0–5:4PC) to DAPC (di5:4PC) (i.e., XH). We also calculated an elastic contribution to γ by the Lo–Ld thickness mismatch, tilt moduli, and bending moduli, as predicted by theory. We found that an increase in XH decreased the overall γ value and the elastic contribution to line tension. The effect on the elastic line tension is driven by a reduced hydrophobic mismatch. Changes in the elastic constants of the phases due to an increase in XH produced a slightly larger elastic γ term. In addition to this elastic energy, other major contributions to γ are found in these model membranes. Increasing XH decreases both elastic and nonelastic contributions to γ. Finally, PAPC also behaves as a linactant, relaxing γ through an interfacial effect, as predicted by theoretical results. This study gives insight into the actual contribution of distinct energy terms to γ in bilayers containing polyunsaturated hybrid lipids.
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