Order Parameter Analysis of Lipids Organization in the Presence of ATP

Adenosine triphosphate (ATP) is an essential component which provides the energy needed in biological interaction in the vicinity of lipid membranes. In this regard, we investigate on the C-D bond order parameter components of phospholipid in presence of ATP for various temperatures obtained by deuterium nuclear magnetic resonance (²H NMR). In addition, simulations were done using a mean-torque potential model to determine the alignment field, which shows the orientational tendency of each carbon segment. We find that the presence of ATP changes the order parameter component as well as the alignment field. These results also indicate that ATP increases membrane order, which results in a stronger alignment field. When increasing temperature, the order parameter goes down because of increasing entropy. These results suggest that the stronger alignment field could influence ion-transport through membranes, which has applications in many biological processes. However, to determine the influence that carbon position and temperature have on this alignment field, more theoretical work is needed.