TY - JOUR
T1 - Material properties of matrix lipids determine the conformation and intermolecular reactivity of diacetylenic phosphatidylcholine in the lipid bilayer
AU - Puri, Anu
AU - Jang, Hyunbum
AU - Yavlovich, Amichai
AU - Masood, M. Athar
AU - Veenstra, Timothy D.
AU - Luna, Carlos
AU - Aranda-Espinoza, Helim
AU - Nussinov, Ruth
AU - Blumenthal, Robert
PY - 2011/12/20
Y1 - 2011/12/20
N2 - Photopolymerizable phospholipid DC 8,9PC (1,2-bis-(tricosa-10,12- diynoyl)-sn-glycero-3-phosphocholine) exhibits unique assembly characteristics in the lipid bilayer. Because of the presence of the diacetylene groups, DC 8,9PC undergoes polymerization upon UV (254 nm) exposure and assumes chromogenic properties. DC 8,9PC photopolymerization in gel-phase matrix lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monitored by UV-vis absorption spectroscopy occurred within 2 min after UV treatment, whereas no spectral shifts were observed when DC 8,9PC was incorporated into liquid-phase matrix 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Liquid chromatography-tandem mass spectrometry analysis showed a decrease in the amount of DC 8,9PC monomer in both DPPC and POPC environments without any change in the matrix lipids in UV-treated samples. Molecular dynamics (MD) simulations of DPPC/DC 8,9PC and POPC/DC 8,9PC bilayers indicate that the DC 8,9PC molecules adjust to the thickness of the matrix lipid bilayer. Furthermore, the motions of DC 8,9PC in the gel-phase bilayer are more restricted than in the fluid bilayer. The restricted motional flexibility of DC 8,9PC (in the gel phase) enables the reactive diacetylenes in individual molecules to align and undergo polymerization, whereas the unrestricted motions in the fluid bilayer restrict polymerization because of the lack of appropriate alignment of the DC 8,9PC fatty acyl chains. Fluorescence microscopy data indicates the homogeneous distribution of lipid probe 1,2-dioleoyl-sn-glycero-3- phosphoethanolamine-N-lissamine rhodamine B sulfonyl ammonium salt (N-Rh-PE) in POPC/DC 8,9PC monolayers but domain formation in DPPC/DC 8,9PC monolayers. These results show that the DC 8,9PC molecules cluster and assume the preferred conformation in the gel-phase matrix for the UV-triggered polymerization reaction.
AB - Photopolymerizable phospholipid DC 8,9PC (1,2-bis-(tricosa-10,12- diynoyl)-sn-glycero-3-phosphocholine) exhibits unique assembly characteristics in the lipid bilayer. Because of the presence of the diacetylene groups, DC 8,9PC undergoes polymerization upon UV (254 nm) exposure and assumes chromogenic properties. DC 8,9PC photopolymerization in gel-phase matrix lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monitored by UV-vis absorption spectroscopy occurred within 2 min after UV treatment, whereas no spectral shifts were observed when DC 8,9PC was incorporated into liquid-phase matrix 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Liquid chromatography-tandem mass spectrometry analysis showed a decrease in the amount of DC 8,9PC monomer in both DPPC and POPC environments without any change in the matrix lipids in UV-treated samples. Molecular dynamics (MD) simulations of DPPC/DC 8,9PC and POPC/DC 8,9PC bilayers indicate that the DC 8,9PC molecules adjust to the thickness of the matrix lipid bilayer. Furthermore, the motions of DC 8,9PC in the gel-phase bilayer are more restricted than in the fluid bilayer. The restricted motional flexibility of DC 8,9PC (in the gel phase) enables the reactive diacetylenes in individual molecules to align and undergo polymerization, whereas the unrestricted motions in the fluid bilayer restrict polymerization because of the lack of appropriate alignment of the DC 8,9PC fatty acyl chains. Fluorescence microscopy data indicates the homogeneous distribution of lipid probe 1,2-dioleoyl-sn-glycero-3- phosphoethanolamine-N-lissamine rhodamine B sulfonyl ammonium salt (N-Rh-PE) in POPC/DC 8,9PC monolayers but domain formation in DPPC/DC 8,9PC monolayers. These results show that the DC 8,9PC molecules cluster and assume the preferred conformation in the gel-phase matrix for the UV-triggered polymerization reaction.
UR - http://www.scopus.com/inward/record.url?scp=83455178197&partnerID=8YFLogxK
U2 - 10.1021/la203453x
DO - 10.1021/la203453x
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C2 - 22053903
AN - SCOPUS:83455178197
SN - 0743-7463
VL - 27
SP - 15120
EP - 15128
JO - Langmuir
JF - Langmuir
IS - 24
ER -