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Understanding the Hofmeister Effect in Interactions between Chaotropic Anions and Lipid Bilayers: Molecular Dynamics Simulations

2003; American Chemical Society; Volume: 125; Issue: 29 Linguagem: Inglês

10.1021/ja0355729

1943-2984

Jonathan N. Sachs, Thomas B. Woolf,

Protein Structure and Dynamics

A set of all-atom molecular dynamics simulations have been performed to better understand critical phenomena regarding a Hofmeister series of anions and lipid bilayers. The simulations isolate the effect of anion size and show clear differences in the interactions with the dipolar phoshpatidylcholine headgroup. Cl- anions penetrate into the headgroup region of the bilayer, but the simulations confirm theories which predict that larger anions penetrate more deeply, into a more heterogeneous and hydrophobic molecular region. That anion size leads to such differences in partitioning in the bilayer provides atomic-level support to hypotheses inspired by several experimental studies. The ability of larger anions to bury deep within the bilayer is correlated with a less well-structured hydration shell, shedding of which upon penetration incurs a smaller penalty for the larger anions than for Cl-.