TY - JOUR

T1 - Membrane-Sugar Interactions Probed by Low-Frequency Raman Spectroscopy

T2 - The Monolayer Adsorption Model

AU - Leonov, Dmitry V.

AU - Dzuba, Sergei A.

AU - Surovtsev, Nikolay V.

N1 - Publisher Copyright: © 2020 American Chemical Society. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/10/6

Y1 - 2020/10/6

N2 - Small sugars are known to stabilize biological membranes under extreme conditions of freezing and desiccation. The proposed mechanisms of stabilization suggest membrane-sugar interactions to be either attractive or repulsive. To obtain new insight into the problem, we use a recently developed low-frequency Raman scattering approach which allows detecting membrane mechanical vibrations. For model membranes of palmitoyl-oleoyl-glycero-phosphocholine (POPC) hydrated in aqueous sucrose and trehalose solutions, we studied the Raman peak between 12 and 15 cm-1 that is attributed to an eigenmode of the normal mechanical vibrations of a lipid monolayer. For both sugars, similar results were obtained. With an increase in sugar concentration in solution, the frequency position of the peak was found to decrease by ∼13% which was interpreted as a consequence of the membrane thickening due sugar monolayer adsorption on the membrane surface. The concentration dependence of the peak frequency position was satisfactorily described by a Langmuir monolayer adsorption model. It is concluded that, at small sugar concentrations (less than 0.2 M), the membrane-sugar interactions are attractive, while at higher concentrations (more than 0.4 M) the attraction disappears. The data obtained show that one sugar molecule on the surface interacts with approximately 3-4 polar lipid heads.

AB - Small sugars are known to stabilize biological membranes under extreme conditions of freezing and desiccation. The proposed mechanisms of stabilization suggest membrane-sugar interactions to be either attractive or repulsive. To obtain new insight into the problem, we use a recently developed low-frequency Raman scattering approach which allows detecting membrane mechanical vibrations. For model membranes of palmitoyl-oleoyl-glycero-phosphocholine (POPC) hydrated in aqueous sucrose and trehalose solutions, we studied the Raman peak between 12 and 15 cm-1 that is attributed to an eigenmode of the normal mechanical vibrations of a lipid monolayer. For both sugars, similar results were obtained. With an increase in sugar concentration in solution, the frequency position of the peak was found to decrease by ∼13% which was interpreted as a consequence of the membrane thickening due sugar monolayer adsorption on the membrane surface. The concentration dependence of the peak frequency position was satisfactorily described by a Langmuir monolayer adsorption model. It is concluded that, at small sugar concentrations (less than 0.2 M), the membrane-sugar interactions are attractive, while at higher concentrations (more than 0.4 M) the attraction disappears. The data obtained show that one sugar molecule on the surface interacts with approximately 3-4 polar lipid heads.

KW - MOLECULAR-DYNAMICS SIMULATIONS

KW - LIPID-BILAYERS

KW - PHASE-SEPARATION

KW - TREHALOSE

KW - SUCROSE

KW - POPC

KW - MECHANISMS

KW - HYDRATION

KW - DPPC

UR - http://www.scopus.com/inward/record.url?scp=85092681537&partnerID=8YFLogxK

U2 - 10.1021/acs.langmuir.0c02458

DO - 10.1021/acs.langmuir.0c02458

M3 - Article

C2 - 32975956

AN - SCOPUS:85092681537

VL - 36

SP - 11655

EP - 11660

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 39

ER -