Study of the interaction of L-cysteine ethyl ester with DPPC membrane

Abstract

Experimental and theoretical studies on the interaction of L-cysteine ethyl ester (ECYS) with dipalmitoylphosphatidylcholine (DPPC) bilayer were carried out. IR and Raman SERS spectra were employed, as previously used for other systems,[1] to follow the changes produced in the DPPC with increasing concentrations of ECYS in the solution. Both states of the lipid, gel and liquid crystalline, were studied at different temperatures. These studies were complemented with Molecular Dynamics simulations that offer a microscopic view of the process [2], monitoring and measuring the importance of the different interactions produced between the ECYS and the bilayer.<br />The shifts of the different IR and Raman signals show a strong interaction with the phosphate group of DPPC, also changes in the region of the C=O groups. The MD reveals that the protonation state of the amino group affect the strength of the interaction with the phosphate group, and the penetration of the probe in the membrane that stay in the region of the ester groups of the lipids.