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- Almstedt, Karin, 1980-, et al.
(författare)
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Unfolding a folding disease: folding, misfolding and aggregation of the marble brain syndrome-associated mutant H107Y of human carbonic anhydrase II
- 2004
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Ingår i: Journal of Molecular Biology. - Oxford : Elsevier. - 0022-2836 .- 1089-8638. ; 342:2, s. 619-633
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Tidskriftsartikel (refereegranskat)abstract
- Most loss-of-function diseases are caused by aberrant folding of important proteins. These proteins often misfold due to mutations. The disease marble brain syndrome (MBS), known also as carbonic anhydrase II deficiency syndrome (CADS), can manifest in carriers of point mutations in the human carbonic anhydrase II (HCA II) gene. One mutation associated with MBS entails the His107Tyr substitution. Here, we demonstrate that this mutation is a remarkably destabilizing folding mutation. The loss-of-function is clearly a folding defect, since the mutant shows 64% of CO2 hydration activity compared to that of the wild-type at low temperature where the mutant is folded. On the contrary, its stability towards thermal and guanidine hydrochloride (GuHCl) denaturation is highly compromised. Using activity assays, CD, fluorescence, NMR, cross-linking, aggregation measurements and molecular modeling, we have mapped the properties of this remarkable mutant. Loss of enzymatic activity had a midpoint temperature of denaturation (Tm) of 16 °C for the mutant compared to 55 °C for the wild-type protein. GuHCl-denaturation (at 4 °C) showed that the native state of the mutant was destabilized by 9.2 kcal/mol. The mutant unfolds through at least two equilibrium intermediates; one novel intermediate that we have termed the molten globule light state and, after further denaturation, the classical molten globule state is populated. Under physiological conditions (neutral pH; 37 °C), the His107Tyr mutant will populate the molten globule light state, likely due to novel interactions between Tyr107 and the surroundings of the critical residue Ser29 that destabilize the native conformation. This intermediate binds the hydrophobic dye 8-anilino-1-naphthalene sulfonic acid (ANS) but not as strong as the molten globule state, and near-UV CD reveals the presence of significant tertiary structure. Notably, this intermediate is not as prone to aggregation as the classical molten globule. As a proof of concept for an intervention strategy with small molecules, we showed that binding of the CA inhibitor acetazolamide increases the stability of the native state of the mutant by 2.9 kcal/mol in accordance with its strong affinity. Acetazolamide shifts the Tm to 34 °C that protects from misfolding and will enable a substantial fraction of the enzyme pool to survive physiological conditions.
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| 3. |
- Agardh, Daniel, et al.
(författare)
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Prediction of silent celiac disease at diagnosis of childhood type 1 diabetes by tissue transglutaminase autoantibodies and HLA
- 2001
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Ingår i: Pediatric Diabetes. - : Hindawi Limited. - 1399-543X. ; 2:2, s. 58-65
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Tidskriftsartikel (refereegranskat)abstract
- Aims: The aims were to estimate the diagnostic sensitivity and specificity of autoantibodies to tissue transglutaminase (IgA- and IgG-tTG), gliadin (AGA) and endomysium (EMA) in relation to human leukocyte antigen (HLA)-DQB1 alleles to identify silent celiac disease at diagnosis of type 1 diabetes. Methods: IgA- and IgG-tTG were measured in radioligand binding assays in 165 type 1 diabetic patients. Data on HLA-DQB1 were available for 148 patients and on both AGA and EMA for 164 patients. For patients considered positive for AGA or EMA, or both, an intestinal biopsy was suggested. HLA-DQB1 typing was carried out by polymerase chain reaction and hybridization with allele specific probes. Results: Three patients, left out from further study of antibodies, but not from HLA-DQB1 analysis, had treated celiac disease at diagnosis. Out of the other 162 type 1 diabetic patients tested, nine had IgA-tTG, six IgG-tTG, eight EMA, and 11 AGA. Biopsy was suggested for nine patients, of whom six showed villous atrophy, one did not and two refused to participate. Thus, silent celiac disease was probable in 8/162 and biopsy-verified in 6/162, where five patients were AGA-positive and six either EMA-, IgA-tTG- or IgG-tTG-positive. Of the 11 patients with celiac disease (three with treated and eight with silent celiac disease), 10 were HLA-DQB1-typed, of whom 65% (13/20) had the DQB1*02 allele, compared with 36% (100/276; p = 0.011) of those without celiac disease. IgA-tTG levels were higher in patients having either *02 or *0302 (0.6; −1.3–112.4 RU) compared with those not having these alleles (0.4; −0.7–3.4 RU; p = 0.023). Conclusion: IgA-tTG are HLA-DQB1*02-associated autoantibodies with high sensitivity and specificity for silent celiac disease at diagnosis of type 1 diabetes.
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| 4. |
- Andersson, Lars Gustaf, et al.
(författare)
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Rifbjerg!
- 2003
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Ingår i: Finns en plats på jorden. - 9163145928
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Analysis of the poem "Rifbjerg!" by Danish writer Klaus Rifbjerg
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| 6. |
- Boldt, Martin, et al.
(författare)
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Exploring Spyware Effects
- 2004
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Konferensbidrag (refereegranskat)abstract
- In this paper, we discuss various types of spyware programs, their behaviour, how they typically infect computers, and the propagation of new varieties of spyware programs. In two experiments, we investigate the occurrence and impact of spyware programs found in popular P2P applications. Based on the findings from the empirical investigations, we try to lift the perspective to a more general view on spyware deriving from the theory of (virtual) network effects. In a model, we categorize in what ways spyware might decrease the utility of belonging to a large virtual network. Here, the baseline is that spyware programs intrude systems and networks, but since they profit from user data they also intrude user privacy. In the model, the intrusions are classified as moderate, severe or disastrous. We found that spyware has the potential to overthrow the positive aspects of belonging to a large network, and network owners should therefore be very careful about permitting such programs in applications and on networks.
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| 10. |
- Carlsson, Bengt, et al.
(författare)
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A biological View on Information Ecosystems
- 2001
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Konferensbidrag (refereegranskat)abstract
- When comparing information ecosystems to biological ecosystems, it becomes clear that both types of systems seem to support robust solutions that are hard to violate for a single agent. In the analysis of information ecosystems, it is important to take into consideration that agents may have a Machiavellian intelligence, i.e., that they take the self-interest of other agents into consideration. We conclude that in the interaction between antagonistic agents within information systems, arms race is a major force. A positive result of this is a better readiness for innocent agents against the vigilant agents. Some examples are given to show how the modelling of information ecosystems in this way can explain the origin of more robust systems when antagonistic agents are around.
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