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- Ali Doosti, Baharan, 1991, et al.
(författare)
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Membrane Tubulation in Lipid Vesicles Triggered by the Local Application of Calcium Ions
- 2017
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 33:41, s. 11010-11017
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Tidskriftsartikel (refereegranskat)abstract
- Experimental and theoretical studies on ion-lipid interactions predict that binding of calcium ions to cell membranes leads to macroscopic mechanical effects and membrane remodeling. Herein, we provide experimental evidence that a point source of Ca2+ acting upon a negatively charged membrane generates spontaneous curvature and triggers the formation of tubular protrusions that point away from the ion source. This behavior is rationalized by strong binding of the divalent cations to the surface of the charged bilayer, which effectively neutralizes the surface charge density of outer leaflet of the bilayer. The mismatch in the surface charge density of the two leaflets leads to nonzero spontaneous curvature. We probe this mismatch through the use of molecular dynamics simulations and validate that calcium ion binding to a lipid membrane is sufficient to generate inward spontaneous curvature, bending the membrane. Additionally, we demonstrate that the formed tubular protrusions can be translated along the vesicle surface in a controlled manner by repositioning the site of localized Ca2+ exposure. The findings demonstrate lipid membrane remodeling in response to local chemical gradients and offer potential insights into the cell membrane behavior under conditions of varying calcium ion concentrations.
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| 3. |
- Brander, Søren, et al.
(författare)
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Biochemical evidence of both copper chelation and oxygenase activity at the histidine brace
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Lytic polysaccharide monooxygenase (LPMO) and copper binding protein CopC share a similar mononuclear copper site. This site is defined by an N-terminal histidine and a second internal histidine side chain in a configuration called the histidine brace. To understand better the determinants of reactivity, the biochemical and structural properties of a well-described cellulose-specific LPMO from Thermoascus aurantiacus (TaAA9A) is compared with that of CopC from Pseudomonas fluorescens (PfCopC) and with the LPMO-like protein Bim1 from Cryptococcus neoformans. PfCopC is not reduced by ascorbate but is a very strong Cu(II) chelator due to residues that interacts with the N-terminus. This first biochemical characterization of Bim1 shows that it is not redox active, but very sensitive to H2O2, which accelerates the release of Cu ions from the protein. TaAA9A oxidizes ascorbate at a rate similar to free copper but through a mechanism that produce fewer reactive oxygen species. These three biologically relevant examples emphasize the diversity in how the proteinaceous environment control reactivity of Cu with O2.
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| 4. |
- Spangfort, M D, et al.
(författare)
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Characterisation of recombinant isoforms of birch pollen allergen Bet v 1
- 1996
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Ingår i: Advances in Experimental Medicine and Biology. - 0065-2598. ; 409, s. 251-254
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Tidskriftsartikel (refereegranskat)abstract
- Three isoforms of the major birch pollen allergen, Bet v, 1 from Betula verrucosa have been expressed as recombinant proteins in E. coli and purified. The immunochemical properties of recombinant isoforms (rBet v 1) differed on immunoblots when compared using Mabs and birch pollen allergic patients serum IgE. 2-D gel analysis showed that recombinant isoforms with different epitope structure can focus under the same protein spot after electrophoresis. The structure of conformational epitopes can be distorted by amino acid substitutions even when T-cell epitopes are not affected as judged by T-cell proliferation studies.
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- Mattsson, Lars-Åke, 1945, et al.
(författare)
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Ultra-low-dose estradiol and norethisterone acetate: bleeding patterns and other outcomes over 52 weeks of therapy.
- 2015
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Ingår i: Climacteric : the journal of the International Menopause Society. - : Informa UK Limited. - 1473-0804. ; 18, s. 419-425
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Tidskriftsartikel (refereegranskat)abstract
- Background Continuous combined hormone replacement therapy (HRT) with 0.5 mg 17β-estradiol (E2) + 0.1 mg norethisterone acetate (NETA) received marketing approval based on 24-week results. The current study collected data up to 52 weeks, including consideration of bleeding, a major reason for stopping HRT. Methods This 52-week (13 lunar-month), non-interventional, prospective study involved 169 women from Norway and Sweden receiving daily oral 0.5 mg E2 + 0.1 mg NETA to treat menopausal symptoms. Incidences and cumulative rates of amenorrhea (no bleeding or spotting) and no bleeding (women could have spotting) were evaluated, together with hot flushes and quality of life. Results Overall, > 78% and > 90% of subjects were amenorrheic or had no bleeding, respectively, in each of the first 3 lunar months, while > 88% and > 96% were amenorrheic or had no bleeding, respectively, in each of lunar months 10, 11 and 12. Cumulative rates of amenorrhea and no bleeding were 67% and 83%, respectively, in lunar months 1-3, and 84% and 94%, respectively, in lunar months 10-12. The number of hot flushes declined during treatment (means at weeks 1, 12 and 52, respectively: 15.5, 5.0 and 4.1 [mild]; 19.0, 3.0 and 2.3 [moderate]; 10.8, 1.1 and 0.9 [severe]). Improvement in all four domains of the Menopause-Specific Quality of Life-Intervention questionnaire (vasomotor, psychosocial, physical and sexual) was evident by week 26. Conclusion For women receiving 0.5 mg E2 + 0.1 mg NETA, lack of bleeding-related side-effects, together with beneficial effects on hot flush symptoms and quality of life, may promote treatment continuance.
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| 7. |
- Rowat, Amy C., et al.
(författare)
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Farnesylated peptides in model membranes: a biophysical investigation
- 2004
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Ingår i: European Biophysics Journal. - : Springer Science and Business Media LLC. - 0175-7571 .- 1432-1017. ; 33:4, s. 300-9
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Tidskriftsartikel (refereegranskat)abstract
- Protein prenylation plays an important role in signal transduction, protein–protein interactions, and the localization and association of proteins with membranes. Using three different techniques, this study physically characterizes the interactions between model dimyristoylphosphatidylcholine membranes and a series of farnesylated peptides. Magic angle spinning nuclear Overhauser enhancement spectroscopy and differential scanning calorimetry reveal that both charged [Ac-Asn-Lys-Asn-Cys-(farnesyl)-OMe and Ac-Asn-Lys-Asn-Cys-(farnesyl)-NH2] and uncharged [Ac-Cys-(farnesyl)-OMe and farnesol] species partition into dimyristoylphosphatidylcholine bilayers. Calorimetry and vesicle fluctuation analysis of giant unilamellar vesicles show that the charged peptides modestly decrease the main gel–fluid phase transition and markedly increase the bending rigidity of large unilamellar vesicles. Uncharged species, on the other hand, dramatically decrease the main phase transition and modestly decrease the bending rigidity. No difference with carboxyl methylation is detected.
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