| 1. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 3. |
- Collinson, Glyn A., et al.
(författare)
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Shocklets and Short Large Amplitude Magnetic Structures (SLAMS) in the High Mach Foreshock of Venus
- 2023
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 50:18
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Tidskriftsartikel (refereegranskat)abstract
- Shocklets and short large-amplitude magnetic structures (SLAMS) are steepened magnetic fluctuations commonly found in Earth's upstream foreshock. Here we present Venus Express observations from the 26th of February 2009 establishing their existence in the steady-state foreshock of Venus, building on a past study which found SLAMS during a substantial disturbance of the induced magnetosphere. The Venusian structures were comparable to those reported near Earth. The 2 Shocklets had magnetic compression ratios of 1.23 and 1.34 with linear polarization in the spacecraft frame. The 3 SLAMS had ratios between 3.22 and 4.03, two of which with elliptical polarization in the spacecraft frame. Statistical analysis suggests SLAMS coincide with unusually high solar wind Alfvén mach-number at Venus (12.5, this event). Thus, while we establish Shocklets and SLAMS can form in the stable Venusian foreshock, they may be rarer than at Earth. We estimate a lower limit of their occurrence rate of ≳14%.
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| 4. |
- Dumoulin, Mireille, et al.
(författare)
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A camelid antibody fragment inhibits the formation of amyloid fibrils by human lysozyme.
- 2003
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 424:6950, s. 783-8
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid diseases are characterized by an aberrant assembly of a specific protein or protein fragment into fibrils and plaques that are deposited in various organs and tissues, often with serious pathological consequences. Non-neuropathic systemic amyloidosis is associated with single point mutations in the gene coding for human lysozyme. Here we report that a single-domain fragment of a camelid antibody raised against wild-type human lysozyme inhibits the in vitro aggregation of its amyloidogenic variant, D67H. Our structural studies reveal that the epitope includes neither the site of mutation nor most residues in the region of the protein structure that is destabilized by the mutation. Instead, the binding of the antibody fragment achieves its effect by restoring the structural cooperativity characteristic of the wild-type protein. This appears to occur at least in part through the transmission of long-range conformational effects to the interface between the two structural domains of the protein. Thus, reducing the ability of an amyloidogenic protein to form partly unfolded species can be an effective method of preventing its aggregation, suggesting approaches to the rational design of therapeutic agents directed against protein deposition diseases.
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| 5. |
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| 6. |
- Morozova-Roche, Ludmilla A, et al.
(författare)
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Amyloid fibril formation and seeding by wild-type human lysozyme and its disease-related mutational variants
- 2000
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Ingår i: Journal of Structural Biology. - : Elsevier BV. - 1047-8477 .- 1095-8657. ; 130:2-3, s. 339-351
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Tidskriftsartikel (refereegranskat)abstract
- Wild-type human lysozyme and its two stable amyloidogenic variants have been found to form partially folded states at low pH. These states are characterized by extensive disruption of tertiary interactions and partial loss of secondary structure. Incubation of the proteins at pH 2.0 and 37 degrees C (Ile56Thr and Asp67His variants) or 57 degrees C (wild-type) results in the formation of large numbers of fibrils over several days of incubation. Smaller numbers of fibrils could be observed under other conditions, including neutral pH. These fibrils were analyzed by electron microscopy, Congo red birefringence, thioflavine-T binding, and X-ray fiber diffraction, which unequivocally show their amyloid character. These data demonstrate that amyloidogenicity is an intrinsic property of human lysozyme and does not require the presence of specific mutations in its primary structure. The amyloid fibril formation is greatly facilitated, however, by the introduction of "seeds" of preformed fibrils to the solutions of the variant proteins, suggesting that seeding effects could be important in the development of systemic amyloidosis. Fibril formation by wild-type human lysozyme is greatly accelerated by fibrils of the variant proteins and vice versa, showing that seeding is not specific to a given protein. The fact that wild-type lysozyme has not been found in ex vivo deposits from patients suffering from this disease is likely to be related to the much lower population of incompletely folded states for the wild-type protein compared to its amyloidogenic variants under physiological conditions. These results support the concept that the ability to form amyloid is a generic property of proteins, but one that is mitigated against in a normally functioning organism.
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