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- Ihalainen, J. A., et al.
(författare)
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Chromophore-Protein Interplay during the Phytochrome Photocycle Revealed by Step-Scan FTIR Spectroscopy
- 2018
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 140:39, s. 12396-12404
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Tidskriftsartikel (refereegranskat)abstract
- Phytochrome proteins regulate many photo-responses of plants and microorganisms. Light absorption causes isomerization of the biliverdin chromophore, which triggers a series of structural changes to activate the signaling domains of the protein. However, the structural changes are elusive, and therefore the molecular mechanism of signal transduction remains poorly understood. Here, we apply twocolor step-scan infrared spectroscopy to the bacteriophytochrome from Deinococcus radiodurans. We show by recordings in H2O and D2O that the hydrogen bonds to the biliverdin D-ring carbonyl become disordered in the first intermediate (Lumi-R) forming a dynamic microenvironment, then completely detach in the second intermediate (Meta-R), and finally reform in the signaling state (Pfr). The spectra reveal via isotope labeling that the refolding of the conserved "PHY-tongue" region occurs with the last transition between Meta-R and Pfr. Additional changes in the protein backbone are detected already within microseconds in Lumi-R Aided by molecular dynamics simulations, we find that a strictly conserved salt bridge between an arginine of the PHY tongue and an aspartate of the chromophore binding domains is broken in Lumi-R and the arginine is recruited to the D-ring C=O. This rationalizes how isomerization of the chromophore is linked to the global structural rearrangement in the sensory receptor. Our findings advance the structural understanding of phytochrome photoactivation.
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- Lindwall, Magnus, 1975, et al.
(författare)
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Method Effects: The Problem With Negatively Versus Positively Keyed Items
- 2012
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Ingår i: Journal of Personality Assessment. - 0022-3891. ; 94:2, s. 196-204
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Tidskriftsartikel (refereegranskat)abstract
- Using confirmatory factor analyses, we examined method effects on Rosenberg's Self-Esteem Scale (RSES; Rosenberg, 1965) in a sample of older European adults. Nine hundred forty nine community-dwelling adults 60 years of age or older from 5 European countries completed the RSES as well as measures of depression and life satisfaction. The 2 models that had an acceptable fit with the data included method effects. The method effects were associated with both positively and negatively worded items. Method effects models were invariant across gender and age, but not across countries. Both depression and life satisfaction predicted method effects. Individuals with higher depression scores and lower life satisfaction scores were more likely to endorse negatively phrased items.
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- Pettersson, K, et al.
(författare)
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Free and complexed prostate-specific antigen (PSA) : in vitro stability, epitope map, and development of immunofluorometric assays for specific and sensitive detection of free PSA and PSA-alpha 1-antichymotrypsin complex
- 1995
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Ingår i: Clinical Chemistry. - 0009-9147. ; 41:10, s. 8-1480
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Tidskriftsartikel (refereegranskat)abstract
- Generation of 15 monoclonal antibodies (MAbs) allowed construction of epitope maps and specific two-site immunofluorometric assays for free prostate-specific antigen (PSA) and PSA complexed with alpha 1-antichymotrypsin (ACT). Close correlation of PSA concentrations obtained with the use of different assays of free PSA suggested extensive similarity in immunodetection of free PSA in serum. Assays of the PSA-ACT complex overestimated the concentration of PSA-ACT in serum because of nonspecific adsorbance of ACT or cathepsin G-complexed ACT to the solid phase. This interference was substantially decreased in the presence of heparin. In studying the stability of purified PSA and PSA-ACT complexes formed in vitro, we found that the free PSA was stable during storage for 4 weeks at 35 degrees C, whereas PSA-ACT complexes largely dissociated in these conditions. The instability of PSA-ACT complexes was counteracted by storage at low temperatures, by adjusting the pH of the storage buffer between 6.8 and 7.4, and through addition of 100-1000-fold molar excess of native ACT. The ease of calibration and the accuracy of free PSA assays in comparison with assays of the PSA-ACT complex suggest that measurements of free to total PSA most accurately reflect the inverse of the proportion of PSA complexed to ACT in serum.
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- Thogersen-Ntoumani, C, et al.
(författare)
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Health and well-being profiles of older European adults
- 2011
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Ingår i: EUROPEAN JOURNAL OF AGEING. - : Springer Science and Business Media LLC. - 1613-9372 .- 1613-9380. ; 8:2, s. 75-85
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to identify health and well-being typologies among a sample of older European adults. Further, we examined various demographic, social, and health behaviour characteristics that were used to discriminate between such groups. The participants were 1,381 community-dwelling adults aged 65 years and above (M age = 73.65; SD = 7.77) from six European Union (EU) countries who completed self-reported questionnaires. Hierarchical cluster analysis was initially conducted followed by a k means analysis to confirm cluster membership. Four clusters were identified and validated: ‘good health and moderate functioning’ (38.40%), ‘moderate health and functioning’ (30.84%), ‘obese and depressed’ (20.24%) and ‘low health and functioning’ (10.51%). The groups could be discriminated based on age, gender, nationality, years of education, social isolation and health behaviours (alcohol consumption and walking behaviour). The results of the study demonstrate heterogeneity with regard to the relationships between the variables examined. The information can be used in targeting older Europeans for health promotion interventions.
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