Impact of sphingomyelin acyl chain (16:0 vs 24:1) on the interfacial properties of Langmuir monolayers: A PM-IRRAS study

Author(s)

Vazquez, Romina F. ^{[1, 2]} ; Daza Millone, Antonieta ^[3] ; Pavinatto, Felippe J. ^{[4, 5]} ; Fanani, Maria L. ^{[6, 7]} ; Oliveira, Jr., Osvaldo N. ^[5] ; Vela, Maria E. ^[3] ; Mate, Sabina M. ^[1]

Affiliation

^[1] Univ Nacl La Plata, Inst Invest Bioquim La Plata INIBIOLP, CCT La Plata, CONICET, Fac Ciencias Med, RA-1900 La Plata, Buenos Aires - Argentina

^[2] Univ Nacl La Plata, Dept Quim, Fac Ciencias Exactas, RA-1900 La Plata, Buenos Aires - Argentina

^[3] Univ Nacl La Plata, Inst Invest Fisicoquim Teor & Aplicadas INIFTA, CCT La Plata, CONICET, Sucursal 4 Casilla Correo 16, RA-1900 La Plata, Buenos Aires - Argentina

^[4] Univ Washington, Clean Energy Inst, Seattle, WA 98195 - USA

^[5] Univ Sao Paulo, Sao Carlos Inst Phys, Sao Paulo, SP - Brazil

^[6] Consejo Nacl Invest Cient & Tecn, Ctr Invest Quim Biol Cordoba CIQUIBIC, Buenos Aires, DF - Argentina

^[7] Univ Nacl Cordoba, Dept Quim Biol Ranwel Caputto, Fac Cs Quim, Ciudad Univ, Cordoba - Argentina

• Document type: Journal article
• Source: COLLOIDS AND SURFACES B-BIOINTERFACES; v. 173, p. 549-556, JAN 1 2019.
• Web of Science Citations: 0

Abstract

Membrane structure is a key factor for the cell's physiology, pathology, and therapy. Evaluating the importance of lipid species such as N-nervonoyl sphingomyelin (24:1-SM) -able to prevent phase separation- to membrane structuring remains a formidable challenge. This is the first report in which polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS) is applied to investigate the lipid-lipid interactions in 16:0 vs 24:1-SM monolayers and their mixtures with 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol (Chol) (DOPC/SM/Chol 2:1:1). From the results we inferred that the cis double bond (Delta 15) in 24:1-SM molecule diminishes intermolecular H-bonding and chain packing density compared to that of 16:0-SM. In ternary mixtures containing 16:0-SM, the relative intensity of the two components of the Amide I band reflected changes in the H-bonding network due to SM-Chol interactions. In contrast, the contribution of the main components of the Amide I band in DOPC/24:1-SM/Chol remained as in 24:1-SM monolayers, with a larger contribution of the non-H-bonded component. The most interesting feature in these ternary films is that the C=O stretching mode of DOPC appeared with an intensity similar to that of SM Amide I band in DOPC/16:0-SM/Chol monolayers (a two-phase {[}Lo/Le] system), whereas an extremely low intensity of the C=0 band was detected in DOPC/24:1-SM/Chol monolayers (single Le phase). This is evidence that the unsaturation in 24:1-SM affected not only the conformational properties of acyl chains but also the orientation of the chemical groups at the air/water interface. The physical properties and overall H-bonding ability conferred by 24:1-SM may have implications in cell signaling and binding of biomolecules. (AU)

• FAPESP's process: 13/14262-7 - Nanostructured films from biologically-relevant materials
• Grantee: Osvaldo Novais de Oliveira Junior
• Support Opportunities: Research Projects - Thematic Grants