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dc.contributor.authorCAFFREY, MARTINen
dc.date.accessioned2011-02-14T12:18:28Z
dc.date.available2011-02-14T12:18:28Z
dc.date.issued1992en
dc.date.submitted1992en
dc.identifier.citationLynch DV, Caffrey M, Hogan J, Steponkus PL, Calorimetric and x-ray diffraction studies of rye glucocerebroside mesomorphism, Biophysical Journal, 61, 5, 1992, 1289-1300en
dc.identifier.otherYen
dc.identifier.urihttp://hdl.handle.net/2262/50537
dc.descriptionPUBLISHEDen
dc.descriptionPMID: 1600084en
dc.description.abstractGlucocerebrosides (GlcCer) isolated from the leaves of winter rye (Secale cereale L. cv Puma) differ from the more commonly investigated natural and synthetic cerebrosides, in that greater than 95% of the fatty acids are saturated and monounsaturated hydroxy fatty acids. Isomers of the trihydroxy long chain base hydroxysphingenine (t1(8:18 cis or trans)) and isomers of sphingadienine (d18:2(4trans, 8 cis or trans)) comprise 77% and 17%, respectively, of the total long chain bases. The phase behavior of fully hydrated and dry rye leaf GlcCer was investigated using differential scanning calorimetry (DSC) and x-ray diffraction. On initial heating, aqueous dispersions of GlcCer exhibit a single endothermic transition at 56 degrees C and have an enthalpy (delta H) of 46 J/g. Cooling to 0 degrees C is accompanied by a small exothermic transition (delta H = -8 J/g) at 8 degrees C. On immediate reheating, a broad exothermic transition (delta H = -39 J/g) is observed between 10 and 20 degrees C in addition to a transition at 56 degrees C. These transitions are not reversible, and the exothermic transition rapidly diminishes when the sample is held at low temperature. Using x-ray diffraction, it was determined that the endotherm at 56 degrees C represents a transition from a highly ordered lamellar crystalline phase (Lc) with a d-spacing of 57 A and a series of wide-angle reflections in the 3-10 A range, to a lamellar liquid crystalline (L alpha) phase having a d-spacing of 55 A and a diffuse wide-angle scattering peak centered at 4.7 A. Cooling leads to the formation of a metastable gel phase (L beta) with a d-spacing of 64.0 A and a single broad reflection at 4.28 A. Subsequent warming to above 15 degrees C restores the original Lc phase. Thus, rye GlcCer in excess water exhibit a series of irreversible transitions and gel phase metastability. Dry GlcCer undergo an initial heating endothermic transition at 130 degrees C, which is ascribed to a transformation into the HII phase from a two phase state characterized by the coexistence of phases with disordered (alpha) and helical (delta) type chain conformations but of unknown lattice identity: An exotherm at 67.5 degrees C observed upon subsequent cooling is of unknown origin. Since an undercooled HII phase persists down to 19 degrees C, the exotherm may derive in part from an alpha-to-delta type chain packing conformational change especially under slow cooling conditions. Upon reheating from low temperatures to 65 degrees C, a phase with a two-dimensional, primitive rectangular lattice and delta-like chain packing (R8 phase) in coexistence with the HI, phase emerges. With continued heating to 90 degrees C these coexisting phases give way to a phase with a two-dimensional, centered rectangular lattice and delta-like chain packing (P8phase) which again coexists with the HI, phase. Above 130 degrees C, the Pb phase disappears and the sample converts completely to the HI, phase as observed upon initial heating. These results indicate that the mesomorphic behavior of rye leaf GIcCer is distinct from that of other cerebrosides.en
dc.description.sponsorshipThis work was supported in part by grants from the United States Department of Agriculture (CG-8801060) and the Department of Energy (DE-FG02-84ER13214) to Peter Steponkus and Daniel Lynch, and the National Institutes of Health (DK 36849) and a University Exploratory Research Program Award (The Procter and Gamble Company) to Martin Caffrey.en
dc.format.extent1289-1300en
dc.language.isoenen
dc.relation.ispartofseriesBiophysical Journalen
dc.relation.ispartofseries61en
dc.relation.ispartofseries5en
dc.rightsYen
dc.subjectBiophysicsen
dc.subjectGlucocerebrosidesen
dc.titleCalorimetric and x-ray diffraction studies of rye glucocerebroside mesomorphismen
dc.typeJournal Articleen
dc.type.supercollectionscholarly_publicationsen
dc.type.supercollectionrefereed_publicationsen
dc.identifier.peoplefinderurlhttp://people.tcd.ie/mcaffreen
dc.identifier.rssinternalid70858en
dc.identifier.rssurihttp://dx.doi.org/10.1016/S0006-3495(92)81937-9en


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