Effect of Macromolecular Crowding Agents on the Packing Properties of Lipid Monolayers

GONZÁLEZ PAZ AGUSTÍN NICOLÁS; ROSA ANTONIO SEBASTIÁN; HUGO A. PÉREZ; DISALVO, ANIBAL; FRÍAS, M. DE LOS ÁNGELES

Córdoba

Congreso; LI Reunión Anual de la Sociedad Argentina de Biofísica; 2023

Sociedad Argentina de Biofísica

Macromolecular crowding affects the structure and function of many enzymes. However,this phenomenon is not an exclusive feature of the cytoplasm and can be observed in thedensely  protein-packed,  nonhomogeneous  cellular  membranes  and  at  the  membraneinterfaces. Two synthetic macromolecular crowders, dextrans and poly(ethylene glycol)s(PEGs) with varying molecular masses affect the structure and function of therapeuticallyimportant enzymes reducing its activity probably through effects on the excluded volumeand reducing the soft interactions.Lipid membranes present a quite similar phenomena in regard to exchange of water interms of excluded volume, confined water and lipid-lipid interactions.In  this  work,  we  have  studied  the  effects  of  two  macromolecular  agents  such  asdextran and PEG on the surface properties of soy phosphadidylcholine lipid monolayersand found that these compounds increase the surface pressure in a similar way as whenthey are compressed by a mobile barrier. This increase is lower when the initial surfacepressure of the monolayer is higher.It is inferred  that the crowding  agents reduces the confined  water between  the lipids,which  is responsible of  the responsiveness of  the membrane to bioeffectors, such  asantioxidants,  oligopeptides  and  aminoacids.  Thus,  the  response  of  the  membrane  tobioeffectors  is  directly  related  to  the  quality  and  amount  of  confined  water,  i.e  theinterfacial water activity.In  this  regard,  these  agents  affect  the  decreases  the  polarizability  of  water  and  thereduces the hydration of phosphates groups as derived from Laurdan fluorescence andFTIR/ATR spectroscopies.This study is helpful for understanding how  crowding may affect lipid membranes in acrowded/cellular environment.