Effects of Phenylalanine on the Liquid Expanded and Liquid Condensed States of Phosphatidylcholine Monolayers

CUTRO ANDREA; ANIBAL E. DISALVO; MARIANGELES FRIAS

lipid insghts

Libertas Academica

Lugar: Aucland; Año: 2019

1178-6353

Phe promotes condensed domains in 1,2-dimyristoyl-sn-glycero-3 (DMPC)monolayers that at 33oC are in the liquid-expanded state and expanded domains in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) that at 20oC are in the liquidcondensedstate. The morphological features examined with Brewster angle microscopy(BAM) indicate condensed particles on a smooth background in Phe/DMPC monolayersand a condensation of particles in Phe/DPPC. The compressibility curves ofDMPC/11mM Phe mixtures at 33 0.2°C are comparable to the mixtures of 9:1DMPC/DPPC indicating that the aminoacid causes an extended condensation of themonolayer. In contrast, DPPC/11mM Phe mixtures show a similar profile than a 1:9DMPC/DPPC mixtures in the absence of Phe which is compatible with an expansion of aliquid condensed phase.DMPC monolayers in the liquid-expanded state show the major response in surfacepressure at 14 mN/m in the concentration range between 0 and 11mM Phe incomparison to DPPC monolayers in the liquid-condensed state.The novelty of this paper is that Phe promotes condensed domains in some expandedenvironments in DPPC and expanded domains in condensed DMPC monolayers. Theresults are congruent with those reported in literature in regard to the coexistence offluid/ condensed domains in DOPC/DPPC mixture and with the proposal that Pheinteracts by forming H bonds with the lipids.