Interaction of Adenosine Triphosphate with Phosphatidylcholine Lipid Bilayers

Abstract

As a polarizable, water soluble molecule, adenosine triphosphate (ATP) can affect the interaction between phosphatidylcholine (PC) lipid bilayers [1, 2]. This is seen by the variation of equilibrium spacings of multilamellar vesicles in ATP solutions that is measured by small-angle x-ray scattering. The most likely scenario is that ATP reduces the van der Waals attraction between PC membranes and at the same time adds an electrostatic repulsion to interbilayer forces by association with lipid headgroups. NMR spectroscopy supports this scenario although it is not yet clear how ATP molecules are distributed at the water-lipid interface. Here we present all-atom molecular dynamics simulations of dilauroyl phosphatidylcholine (DLPC) in the presence of ATP. All-atom simulations containing 100 DLPC lipids and were run in NAMD using the CHARMM force field at 310 K. We present the spatial distribution of ATP molecules as seen in simulations in relation to x-ray and NMR results. [1] Koerner et al, Biophys. J. 2011, [2] Johnson et al., Langmuir 2014.