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  • Daniel Otzen Group: Home

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  • Daniel Otzen Group: Aggregation
    tendency to do so during production in the pharmaceutical industry We have carried out numerous studies of how different types of fibrils are formed under different circumstances illustrating the principle of fibrillar polymorphism 14 25 This has been summarized in several reviews 26 27 S6 ribosomal protein from T thermophilus With the study of fibrillation of S6 at low pH we were the first group to publish a detailed protein engineering study of a protein that can be induced to fibrillate with a pronounced lag time from a quasi native state demonstrating that fibrillation requires partially unfolded regions and that minimization of the backbone by truncation to alanine favours this process 28 Protein fibrillation Membrane proteins Protein detergent interactions REFERENCES 1 Giehm L Oliveira C L P Christiansen G Pedersen J S and Otzen D E 2010 SDS induced fibrillation of α synuclein An alternative fibrillation pathway Journal of Molecular Biology 401 115 133 2 Giehm L Svergun D I Otzen D E and Vestergaard B 2011 Low resolution structure of a vesicle disrupting α synuclein oligomer that accumulates during fibrillation Proc Natl Acad Sci U S A 108 3246 3251 3 Kjær L Giehm L Heimburg T and Otzen D E 2009 The influence of vesicle composition and size on synuclein structure and stability Biophys J 96 2857 2870 4 Giehm L Lorenzen N and Otzen D E 2010 Assays for α synuclein aggregation In Methods Cyr D Ed Elsevier 5 Giehm L and Otzen D E 2010 Strategies to increase the reproducibility of α synuclein fibrillation in plate reader assays Anal Biochem 400 270 281 6 Runager K Basaiawmoit R V Deva T Andreasen M Valnickova Z Sørensen C S Karring H Thøgersen I B Christiansen G Underhaug J Kristensen T Nielsen N C Klintworth G K Otzen D E and Enghild J J 2011 Human phenotypically distinct TGFI corneal dystrophies are linked to the stability of the fourth Fas1 domain of TGFBIp J Biol Chem 286 4951 4958 7 Dueholm M Nielsen S B Hein K L Nissen P Chapman M R Christiansen G Nielsen P H and Otzen D E 2011 Fibrillation of the Major Curli Subunit CsgA under changing conditions implies robust design of aggregation Biochemistry In press 8 Larsen P Dueholm M Christiansen G Nielsen J L Otzen D E and Nielsen P H 2007 Amyloid adhesins are abundant in natural biofilms Env Microbiol 9 3077 3090 9 Larsen P Nielsen J L Otzen D E and Nielsen P H 2008 Amyloid like adhesins in floc forming and filamentous bacteria in activated sludge Appl Env Microbiol 74 1517 1526 10 Jordal P B Dueholm M Larsen P Pedersen S V Enghild J J Christiansen G Højrup P Nielsen P H and Otzen D E 2009 Widespread abundance of Functional Bacterial Amyloid in Mycolata and other Gram positive Bacteria Appl Env Microbiol 75 4101 4110 11 Dueholm M S Petersen S V Sønderkær M Larsen P Christiansen G Hein K L Enghild J J Nielsen

    Original URL path: http://www.proteins.dk/fibrillation.html (2016-05-02)
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  • Daniel Otzen Group: Membrane proteins
    together by the assembly of the transmembrane helices which then act as an organizing scaffold The autotransporter AIDA The bacterial outer membrane protein AIDA Adhesin Involved in Diffuse Adherence is an autotransporter and as such it inserts spontaneously in the outer membrane via the 336 residue b domain after which the 900 residue a domain is translocated across the outer membrane to be displayed on the surface We have recently reported a detailed study of the folding of the isolated b domain 13 which shows that it can only be refolded when immobilized on a column attempts to refold it in solution leads to misfolded states which display cooperative unfolding but remain proteolytically sensitive and lack the band shift upon heating which is characteristic of folded outer membrane proteins We have been unable to identify any periplasmic factors including purified periplasmic chaperones which might help folding of this domain suggesting that an interaction mediated by the a domain might facilitate folding in prep and 14 The folded state of AIDA can be unfolded in the presence of SDS only at high temperatures and there is a linear relationship between the SDS mole fraction and the melting temperature 13 A very detailed study of thermal scans in the presence of various detergents has shown that it is the micellar rather than bulk detergent composition that is the appropriate parameter to use in this analysis 15 Complementary to this work we have also studied the interactions between different detergents and lipids by spectroscopic and surface tension techniques This sheds more light on the characteristics of mixed micelle systems which is central to our analysis of membrane protein behaviour in amphiphiles 16 17 The outer membrane protein OmpA OmpA is one of the most well studied outer membrane proteins OMPs and is also

    Original URL path: http://www.proteins.dk/membrane.html (2016-05-02)
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  • Daniel Otzen Group: Protein detergent interactions
    water 4 More recently we have demonstrated a remarkable ability of different detergents at the monomer level in activating and inhibiting lipase activity 21 an activity which traditionally has been regarded as requiring an aggregated detergent rather than monomer We have systematically analyzed the unfolding of model proteins from different structural classes to extract more general principles for detergent protein interactions 5 10 Together with Professor Jan Skov Pedersen we have made significant advances using Small Angle X ray Scattering and have developed a model see below taken from 6 in which several proteins contribute detergent micelles to come together as a shared micelle Our work has been reviewed recently 11 Protein fibrillation Membrane proteins Protein detergent interactions REFERENCES 1 Otzen D E 2002 Protein unfolding in detergents Effect of micelle structure ionic strength pH and temperature Biophys J 83 2219 2230 2 Otzen D E and Oliveberg M 2002 Burst phase expansion of native protein prior to global unfolding in SDS Journal of Molecular Biology 315 1231 1240 3 Otzen D E Christiansen L and Schülein M 1999 A comparative study of the unfolding of the endoglucanase Cel45 from Humicola insolens in denaturant and surfactant Prot Sci 8 1878 1887 4 Otzen D E and Oliveberg M 2001 A simple way to measure protein refolding rates in water Journal of Molecular Biology 313 479 483 5 Andersen K Westh P and Otzen D E 2008 A global study of myoglobin surfactant interactions Langmuir 15 399 407 6 Andersen K K Oliveira C L P Larsen K L Poulsen F M Callisen T H Westh P Pedersen J S and Otzen D E 2009 The role of decorated SDS micelles in sub cmc protein denaturation and association Journal of Molecular Biology 391 207 226 7 Andersen K K and Otzen

    Original URL path: http://www.proteins.dk/detergent.html (2016-05-02)
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  • Daniel Otzen Group: News
    Group News Your browser does not support iframes Research Home News Daniel Otzen Research Publication List Lab Facilities Funding The Group Team Members Alumni Available projects Social Internal Links Equipment

    Original URL path: http://www.proteins.dk/News.html (2016-05-02)
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  • Daniel Otzen Group: Daniel Otzen
    Erik Otzen Curriculum Vitea Your browser does not support iframes Research Home News Daniel Otzen Research Publication List Lab Facilities Funding The Group Team Members Alumni Available projects Social Internal

    Original URL path: http://www.proteins.dk/danielotzen.html (2016-05-02)
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  • Daniel Otzen Group: Research
    rich protein fibrils or amyloid We focus on several different issues 1 How do proteins aggregate and lead to diseases such as Alzheimer s and Parkinson s but also serve useful purposes in forming bacterial amyloid 2 How do surfactants and biosurfactants affect protein structure stability and function 3 How are membrane proteins tuned to fold in a membrane environment Technology We follow the structural and energetic changes involved in these processes using many different complementary techniques 1 Secondary structure far UV circular dichroism Fourier Transform Infrared Spectroscopy 2 Tertiary structure fluorescence near UV circular dichroism 3 Kinetics of these changes rapid reactions by stopped flow kinetics slow reactions over hours days in plate readers 4 Thermodynamics of structural changes isothermal titration calorimetry differential scanning calorimetry 5 The types of aggregates formed during protein aggregation and their o size size separation by field flow fractionation gel filtration and size quantification by static dynamic light scattering and o effect on membranes release of membrane contents 6 Imaging of aggregates and membranes by Atomic Force Microscopy electron microscopy and Laser Confocal Scanning Microscopy 7 Binding of aggregates and proteins to surfaces quartz crystal microbalance 8 Structures of aggregates and complexes at the

    Original URL path: http://www.proteins.dk/research.html (2016-05-02)
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  • Daniel Otzen Group: Publications List
    Daniel Otzen 1993 2013 Your browser does not support iframes Research Home News Daniel Otzen Research Publication List Lab Facilities Funding The Group Team Members Alumni Available projects Social Internal

    Original URL path: http://www.proteins.dk/publications.html (2016-05-02)
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