tailieunhanh - Báo cáo Y học: Biophysical characterization of the interaction of high-density lipoprotein (HDL) with endotoxins

The interaction of bacterial endotoxins [lipopolysaccharide (LPS) and the endotoxic principle lipid A], with high-den-sity lipoprotein (HDL) from serum was investigated with a variety of physical techniques and biological assays. HDL exhibited an increase in the gel to liquid crystalline phase transition temperature Tc and a rigidification of the acyl chains of the endotoxins as measured by Fourier-transform infrared spectroscopy and differential scanningcalorimetry. | Eur. J. Biochem. 269 5972-5981 2002 FEBS 2002 doi Biophysical characterization of the interaction of high-density lipoprotein HDL with endotoxins Klaus Brandenburg1 Gudrun Jurgens1 Jorg Andra1 Buko Lindner1 Michel H. J. Koch2 Alfred Blume3 and Patrick Garidel3 1Forschungszentrum Borstel Biophysik Borstel Germany 2European Molecular Biology Laboratory Hamburg Outstation EMBL c o DESY Hamburg Germany 3Martin-Luther-Universităt Halle Wittenberg Institut fur Physikalische Chemie Halle Germany The interaction of bacterial endotoxins lipopolysaccharide LPS and the endotoxic principle lipid A with high-density lipoprotein HDL from serum was investigated with a variety of physical techniques and biological assays. HDL exhibited an increase in the gel to liquid crystalline phase transition temperature Tc and a rigidification of the acyl chains of the endotoxins as measured by Fourier-transform infrared spectroscopy and differential scanning Cillori metry. The functional groups of the endotoxins interacting with HDL are the phosphates and the diglucosamine backbone. The findingof phosphates as target groups is in accordance to measurements of the electrophoretic mobility showing that the zeta potential decreases from -50 to -60 mV to -20 mV at binding saturaiion. The importance of the sugar backbone as further target structure is in accordance with the remainingnegative potential and competition experiments with polymyxin B PMB and phase transition data of the system PMB dephosphorylated LPS. Furthermore endotoxin binding to HDL ình lienees the secondaiy tr 1 re of the latter manifesting m a changf from a míxed a-helical b-sheet structure to a predominantly a-helical structure. The aggregate structure of the lipid A moiety of the endotoxins as determined by small-angle X-ray scattering shows a change of a unilamellar inverted cubic into a multilamellar structure in the presence of HDL. Fluorescence resonance energy transfer data .