Interaction of cysteine and its derivatives with monolayers of dipalmitoylphosphatidylcholine

JUAN M. ARIAS; SONIA B. DÍAZ; AIDA BEN ALTABEF; FERNANDO G. DUPUY

COLLOIDS AND SURFACES B-BIOINTERFACES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019 vol. 184

0927-7765

Molecular interactions between L-cysteine (Cys) and its ester derivatives (Cysx); L-cysteine ethyl ester (CE), Lcysteinemethyl ester (CM) and N-acetyl L-cysteine (NAC) with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine(DPPC) monolayers were investigated using Langmuir film balance technique. The effect of charge on monolayersmade of cysteine and three ester derivatives with DPPC was investigated by working with un-buffered andbuffered subphases. Also, the effects of cysteine derivatives interaction with DPPC monolayers were studiedmeasuring the change in the surface tension upon aminoacid injection in the subphase whilst keeping lipidmolecular density and lateral packing controlled.Cysteine and its ester derivatives showed interfacial activity reducing the air/water surface tension (πi) by4mNm−1. However, ester derivatives were able to insert into preformed DPPC monolayers at much highersurface pressures (Δπ), indicating a preferential interaction of Cysx with DPPC.The results indicate that, although the different derivatives of cysteine presented low surface activity, theywere able to favourably interact with DPPC monolayers. Also, compression isotherms experiments in binarymixtures indicate that the more surface active compounds stabilized the gel phase of DPPC. The charge oncysteine and its derivatives did not increase the observed effects.