1.Effect of cholesterol on binding of amphipathic helices to lipid emulsions.
Ozawa M1, Handa T, Nakano M. J Phys Chem B. 2012 Jan 12;116(1):476-82. doi: 10.1021/jp207062h. Epub 2011 Dec 13.
Plasma triglyceride-rich lipoproteins vary in their lipid composition during metabolism. We investigated the effects of cholesterol (Chol) on the surface properties of lipid emulsions and on the interactions with two amphipathic peptides, acetyl-DWLKAFYDKVAEKLKEAF-amide (Ac-18A-NH(2)) and acetyl-KWLDAFYDEVAEKLKKAF-amide (Ac-18G*-NH(2)), which differ in charge distribution. The fluorescence lifetimes of N-dansyl phosphatidylethanolamine (dansyl-PE) and n-(9-anthroyloxy)stearic acid (n-AS, n = 2, 6, and 12) were used to assess the water penetration into the headgroup and acyl chain regions of phosphatidylcholine (PC), respectively. Steady-state fluorescence anisotropy of n-AS was also performed to evaluate the acyl chain fluidity in emulsion surface monolayers. Chol decreased the fluorescence lifetime of dansyl-PE and increased the lifetimes and anisotropy values of n-AS. These results demonstrated that Chol alters the surface properties of emulsions, i.
2.Amphiphilic effects of dibucaine HCl on rotational mobility of n-(9-anthroyloxy)stearic acid in neuronal and model membranes.
Lee YH1, Park NS, Kwon JD, Park JS, Shin GB, Lee CS, Jung TS, Choi NJ, Yoon JH, Ok JS, Yoon UC, Bae MK, Jang HO, Yun I. Chem Phys Lipids. 2007 Mar;146(1):33-42. Epub 2006 Dec 30.
We studied dibucaine's effects on specific locations of n-(9-anthroyloxy)palmitic acid or stearic acid (n-AS) within phospholipids of synaptosomal plasma membrane vesicles isolated from bovine cerebral cortex (SPMV) and model membranes. Giant unilamellar vesicles (GUVs) were prepared with total lipids (SPMVTL) and mixture of several phospholipids (SPMVPL) extracted from SPMV. Dibucaine.HCl increased rotational mobility (increased disordering) of hydrocarbon interior, but it decreased mobility (increased ordering) of membrane interface, in both native and model membranes. The degree of rotational mobility in accordance with the carbon atom numbers of phospholipids comprising neuronal and model membranes was in the order at the 16, 12, 9, 6 and 2 position of aliphatic chain present in phospholipids. The sensitivity of increasing or decreasing effect of rotational mobility of hydrocarbon interior or surface region by dibucaine.HCl differed depending on the neuronal and model membranes in the descending order of SPMV, SPMVPL and SPMVTL.
3.Incorporation of fluorescent probes into PAMAM dendrimers.
Domański DM1, Klajnert B, Bryszewska M. Bioelectrochemistry. 2004 Jun;63(1-2):193-7.
Interactions of two fluorescent probes 1-(trimethylammoniumphenyl)-6-phenyl-1,3,5 hexatriene p-toluenesulfonate (TMA-DPH) and 12-(9-anthroyloxy) stearic acid (12-AS) with polyamidoamine (PAMAM) dendrimers were studied. Changes in fluorescence intensity and steady-state fluorescence anisotropy of TMA-DPH and 12-AS were monitored. It was found that 12-AS molecules incorporated into dendrimer cavities whereas TMA-DPH molecules aggregated on the surface of polymer. Dendrimer size had not significant impact on its host properties.
4.The effect of methanol on the structural parameters of neuronal membrane lipid bilayers.
Joo HJ1, Ahn SH, Lee HR, Jung SW, Choi CW, Kim MS, Bae MK, Chung IK, Bae SK, Jang HO, Yun I. Korean J Physiol Pharmacol. 2012 Aug;16(4):255-64. doi: 10.4196/kjpp.2012.16.4.255. Epub 2012 Aug 10.
The structures of the intact synaptosomal plasma membrane vesicles (SPMVs) isolated from bovine cerebral cortexs, and the outer and the inner monolayer separately, were evaluated with 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1,3-di(1-pyrenyl)propane (Py-3-Py) as fluorescent reporters and trinitrophenyl groups as quenching agents. The methanol increased bulk rotational and lateral mobilities of SPMVs lipid bilayers. The methanol increased the rotational and lateral mobilities of the outer monolayers more than of the inner monolayers. n-(9-Anthroyloxy)stearic acid (n-AS) were used to evaluate the effect of the methanol on the rotational mobility at the 16, 12, 9, 6, and 2 position of aliphatic chains present in phospholipids of the SPMVs outer monolayers. The methanol decreased the anisotropy of the 16-(9-anthroyloxy)palmitic acid (16-AP), 12-(9-anthroyloxy)stearic acid (12-AS), 9-(9-anthroyloxy)stearic acid (9-AS), and 6-(9-anthroyloxy)stearic acid (6-AS) in the SPMVs outer monolayer but it increased the anisotropy of 2-(9-anthroyloxy)stearic acid (2-AS) in the monolayers.