tailieunhanh - Báo cáo khoa học: Effects of sphingomyelin, cholesterol and zinc ions on the binding, insertion and aggregation of the amyloid Ab1)40 peptide in solid-supported lipid bilayers

We utilized plasmon-waveguide resonance (PWR) spectroscopy to follow the effects of sphingomyelin, cholesterol and zinc ions on the binding and aggregation of the amyloidbpeptide1)40 in lipid bilayers. With a dioleoyl-phosphatidylcholine (DOPC) bilayer, peptide binding was observed, but no aggregation occurred over a period of 15 h. | ềFEBS Journal Effects of sphingomyelin cholesterol and zinc ions on the binding insertion and aggregation of the amyloid Ab1_40 peptide in solid-supported lipid bilayers Savitha Devanathan1 Zdzislaw Salamon1 Goran Lindblom1 Gerhard Grobner2 and Gordon Tollin1 1 Department of Biochemistry and Molecular Biophysics University of Arizona Tucson AZ USA 2 Department of BiophysicalChemistry Umea University Sweden Keywords Alzheimer s disease amyloid toxicity microdomains plasmon-waveguide resonance spectroscopy rafts Correspondence G. Tollin Department of Biochemistry and Molecular Biophysics University of Arizona Tucson AZ 85721 USA Fax 1 520 621 9288 Tel 1 520 621 3447 E-mail gtollin@ Received 8 December 2005 revised 25 January 2006 accepted 2 February 2006 doi We utilized plasmon-waveguide resonance PWR spectroscopy to follow the effects of sphingomyelin cholesterol and zinc ions on the binding and aggregation of the amyloid b peptide1_40 in lipid bilayers. With a dioleoylphosphatidylcholine DOPC bilayer peptide binding was observed but no aggregation occurred over a period of 15 h. In contrast similar binding was found with a brain sphingomyelin SM bilayer but in this case an exponential aggregation process was observed during the same time interval. When the SM bilayer included 35 cholesterol an increase of occurred in the amount of peptide bound with a similar increase in the extent of aggregation the latter resulting in decreases in the bilayer packing density and displacement of lipid. Peptide association with a bilayer formed from equimolar amounts of DOPC SM and cholesterol was followed using a high-resolution PWR sensor that allowed microdomains to be observed. Biphasic binding to both domains occurred but predominantly to the SM-rich domain initially to the surface and at higher peptide concentrations within the interior of the bilayer. Again aggregation was observed and occurred within both microdomains