Trehalose and arbutin interactions with model pc membranes: a molecular dynamic (md) simulation study

NICASTRO, ALCIDES; GARAY, ALBERTO S.; CREUS, AGUSTINA; FRÍAS, MARÍA A.; DISALVO, ANÍBAL E.; RODRIGUES, DANIEL E.

Buzios, Río de Janeiro, Brasil

Congreso; Biophysics 2009, VII Congreso Iberoamericano de Biofísica; 2009

Sociedad de Biofísica de Brasil y Argentina, IUPAB

Polihydroxilated molecules are known by its ability to preserve the integrity of biomembranes when subjected to low temperatures or dehydration. Despite of the extensive application of this recipe, the physicochemical processes involved are not yet fully understood. One of the experimental tools of election to study the problem is FTIR spectroscopy of model bilayers. Nevertheless the proposal of microscopic models based on FTIR requires the use of simulations. We have studied the interaction of isolated polihydroxilated (Ph) molecules (Trehalose and Arbutin) with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) hydrated bilayers in the La phase using MD. The MDs were performed in a PZgT ensemble where surface tension g has been adjusted to reproduce the Deuterium order parameter profiles. The resultant area/lipid is (58,1±0.6)Å2 in agreement with X-ray and neutron diffraction experiments. We found that when the trehalose approximates to the interface builds an average of 2.6±1.3 H-bonds (HB) to the lipid heads and a maximum of 6 (2.5±0.7 and 3 for arbutin). These quantities of Ph-lipid HB do not compensate for the total loss of water-lipid HB that take place after the Ph absorption (6.8 and 6.0 for trehalose and arbutin respectively). For both cases the most notable loss of water-lipid HB not compensated by Ph-lipid HB is that of the phosphate esther oxygens. The carbonyl oxygens experiments a larger loss of water-HB uncompensated by Ph HB on the Sn2- than on the Sn1 alkyl chain after trehalose absorption. Conversely following Arbutin absorption only the quantity of uncompensated water-lipid HB of the carbonyl Sn1 are affected. The implications on the interpretation of FTIR spectra are analyzed.