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111.
112.
Lassiseraye D Courtemanche L Bergeron A Manjunath P Lafleur M 《Biochimica et biophysica acta》2008,1778(2):502-513
Bovine seminal plasma (BSP) contains a family of phospholipid-binding proteins. The affinity of the protein BSP-A1/-A2 for lipid membranes composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and POPC containing 30% (mol/mol) 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) or cholesterol, has been investigated by the isothermal titration calorimetry (ITC). This study confirms the association of these proteins to lipid bilayers, and provides a direct characterization of this exothermic process, at 37 degrees C. The measurements indicate that the protein affinity for lipid bilayers is modulated by the lipid composition, the lipid/protein ratio, and the temperature. The saturation lipid/protein ratio was increased in the presence of cholesterol and, to a lesser extent, of phosphatidylethanolamine, suggesting that it is modulated by the lipid acyl chain order. For all the investigated systems, the binding of BSP-A1/-A2 could not be modeled using a simple partitioning of the proteins between the aqueous and lipid phases. The existence of "binding sites", and lipid phase separations is discussed. The decrease of temperature, from 37 to 10 degrees C, converts the exothermic association of the proteins to the POPC bilayers to an endothermic process. A complementary 1-D and 2-D infrared spectroscopy study excludes the thermal denaturation of BSP-A1/-A2 as a contributor in the temperature dependence of the protein affinity for lipid bilayers. The reported findings suggest that changes in the affinity of BSP-A1/-A2 for lipid bilayers could be involved in modulating the association of these proteins to sperm membranes as a function of space and time; this would consequently modulate the extent of lipid extraction, including cholesterol, at a given place and given time. 相似文献
113.
Despite numerous investigations, the important structural features of Cell Penetrating Peptides (CPPs) remain unclear as demonstrated by the difficulties encountered in designing new molecules. In this study, we focused our interest on Penetratin and Transportan and several of their variants. Penetratin W48F and Penetratin W48F/W56F exhibit a reduced and a complete lack of cellular uptake, respectively; TP07 and TP10 present a similar cellular uptake as Transportan and TP08, TP13 and TP15 display no or weak internalization capacity. We applied the algorithmic method named PepLook to analyze the peptide polymorphism. The study reveals common conformational characteristics for the CPPs and their permeable variants: they all are polymorphic. Negative, non permeable, mutants share the opposite feature since they are monomorphic. Finally, we support the hypothesis that structural polymorphism may be crucial since it provides peptides with the possibility of adapting their conformation to medium hydrophobicity and or to partner diversity. 相似文献
114.
115.
Marsault E Hoveyda HR Gagnon R Peterson ML Vézina M Saint-Louis C Landry A Pinault JF Ouellet L Beauchemin S Beaubien S Mathieu A Benakli K Wang Z Brassard M Lonergan D Bilodeau F Ramaseshan M Fortin N Lan R Li S Galaud F Plourde V Champagne M Doucet A Bhérer P Gauthier M Olsen G Villeneuve G Bhat S Foucher L Fortin D Peng X Bernard S Drouin A Déziel R Berthiaume G Dory YL Fraser GL Deslongchamps P 《Bioorganic & medicinal chemistry letters》2008,18(16):4731-4735
A new method for solid phase parallel synthesis of chemically and conformationally diverse macrocyclic peptidomimetics is reported. A key feature of the method is access to broad chemical and conformational diversity. Synthesis and mechanistic studies on the macrocyclization step are reported. 相似文献
116.
Lactoferrin and host defence: an overview of its immuno-modulating and anti-inflammatory properties 总被引:1,自引:0,他引:1
Lactoferrin is a member of the transferrin family of iron-binding glycoproteins that is abundantly expressed and secreted from glandular epithelial cells. In secretions, such as milk and fluids of the intestinal tract, lactoferrin is an important component of the first line of host defence. During the inflammatory process, lactoferrin, a prominent component of the secondary granules of neutrophils (PMNs), is released in infected tissues and in blood and then it is rapidly cleared by the liver. In addition to the antimicrobial properties of lactoferrin, a set of studies has focused on its ability to modulate the inflammatory process and the overall immune response. Though many in vitro and in vivo studies report clear regulation of the immune response and protective effect against infection and septic shock by lactoferrin, elucidation of all the cellular and molecular mechanisms of action is far from being achieved. At the cellular level, lactoferrin modulates the migration, maturation and function of immune cells. At the molecular level and in addition to iron binding, interactions of lactoferrin with a plethora of compounds, either soluble or membrane molecules, account for its modulatory properties. This paper reviews our current understanding of the cellular and molecular mechanisms that explain the regulatory properties of lactoferrin in host defence. 相似文献
117.
Bernard Pineau Jacqueline Girard-Bascou Stephan Eberhard Yves Choquet Antoine Trémolières Catherine Gérard-Hirne Annick Bennardo-Connan Paulette Decottignies Sylvie Gillet Francis-André Wollman 《European journal of biochemistry》2004,271(2):329-338
Two mutants of Chlamydomonas reinhardtii, mf1 and mf2, characterized by a marked reduction in their phosphatidylglycerol content together with a complete loss in its Delta3-trans hexadecenoic acid-containing form, also lost photosystem II (PSII) activity. Genetic analysis of crosses between mf2 and wild-type strains shows a strict cosegregation of the PSII and lipid deficiencies, while phenotypic analysis of phototrophic revertant strains suggests that one single nuclear mutation is responsible for the pleiotropic phenotype of the mutants. The nearly complete absence of PSII core is due to a severely decreased synthesis of two subunits, D1 and apoCP47, which is not due to a decrease in translation initiation. Trace amounts of PSII cores that were detected in the mutants did not associate with the light-harvesting chlorophyll a/b-binding protein antenna (LHCII). We discuss the possible role of phosphatidylglycerol in the coupled process of cotranslational insertion and assembly of PSII core subunits. 相似文献
118.
Bovine seminal plasma (BSP) contains a family of phospholipid-binding proteins. The affinity of the protein BSP-A1/-A2 for lipid membranes composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and POPC containing 30% (mol/mol) 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) or cholesterol, has been investigated by the isothermal titration calorimetry (ITC). This study confirms the association of these proteins to lipid bilayers, and provides a direct characterization of this exothermic process, at 37 °C. The measurements indicate that the protein affinity for lipid bilayers is modulated by the lipid composition, the lipid/protein ratio, and the temperature. The saturation lipid/protein ratio was increased in the presence of cholesterol and, to a lesser extent, of phosphatidylethanolamine, suggesting that it is modulated by the lipid acyl chain order. For all the investigated systems, the binding of BSP-A1/-A2 could not be modeled using a simple partitioning of the proteins between the aqueous and lipid phases. The existence of "binding sites", and lipid phase separations is discussed. The decrease of temperature, from 37 to 10 °C, converts the exothermic association of the proteins to the POPC bilayers to an endothermic process. A complementary 1-D and 2-D infrared spectroscopy study excludes the thermal denaturation of BSP-A1/-A2 as a contributor in the temperature dependence of the protein affinity for lipid bilayers. The reported findings suggest that changes in the affinity of BSP-A1/-A2 for lipid bilayers could be involved in modulating the association of these proteins to sperm membranes as a function of space and time; this would consequently modulate the extent of lipid extraction, including cholesterol, at a given place and given time. 相似文献
119.
Borges JP Barre A Culerrier R Granier C Didier A Rougé P 《Biochemical and biophysical research communications》2008,365(4):685-690
Four IgE-binding epitopes have been characterized that cover a large area (40%) of the molecular surface of lipid transfer protein allergens of Rosaceae (apple, peach, apricot, and plum). They mainly correspond to electropositively charged regions protruding on the molecular surface of the modeled apple (Mal d 3), apricot (Pru ar 3), and plum (Pru d 3) allergens. Two of these epitopes consist of consensus epitopes structurally conserved among the lipid transfer protein allergens from the Rosaceae. Their occurrence in different lipid transfer protein allergens presumably accounts for the IgE-binding cross-reactivity often observed among different Rosaceae fruits. In this respect, LTP consist of phylogenetically- and structurally-related pan allergens. However, the IgE-binding cross-reactivity due to fruit lipid transfer protein has varying degrees of clinical relevance and this cross-reactivity is not necessarily accompanied by a cross-allergenicity to the corresponding fruits. 相似文献
120.
We investigated the peptides N-acetyl-AWYIK-amide and N-acetyl-VWYIK-amide corresponding to single amino acid substitutions in LWYIK, a segment found in the gp41 protein of HIV and believed to play a role in sequestering this protein to a cholesterol-rich domain in the membrane. The effects of these peptides on the thermotropic phase transitions of 1-stearoyl-2-oleoylphosphatidylcholine (SOPC) and mixtures of SOPC and cholesterol were intermediate between that having the wild-type sequence (LWYIK) and another (IWYIK), the least active peptide previously studied. This correlated with results from studies of single mutations in the gp41 protein of HIV-1, in which L679 of the LWYIK segment is replaced with either A or V, measuring the capability of TZM-BL HeLa-based HIV-1 indicator cells to form syncytia. The peptides were also comparatively analyzed in silico. All together, the results suggest that the mode of interaction of this region of gp41 with the polar heads of membrane lipids contributes to its cholesterol selectivity and that this is somehow related to the biological activity of the viral glycoprotein. 相似文献