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Daniel E. Otzen


Our research activities fall within 3 main areas: membrane protein foldingprotein-detergent interactions and protein fibrillation. In all cases, we study the different steps by which proteins change their structure under different circumstances, whether it be the process of inserting into a membrane or detergent micelle or the assembly into long β-sheet 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
    1. o size(size separation by field flow fractionation/gel filtration and size quantification by static/dynamic light scattering) and
    2. 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 nm-level by Small Angle X-ray scattering (with Professor Jan Skov Pedersen, Department of Chemistry) and solid-state NMR (with Professor Niels Chr. Nielsen, Department of Chemistry)

Our research activities fall within 3 main areas, which all relate to the study of the kinetics and thermodynamics of protein conformational changes, namely membrane protein folding, protein-detergent interactions and protein fibrillation. These areas are linked by a keen interest in understanding the mechanistic and thermodynamic behaviour of proteins in different circumstances by quantifying the strength of internal side-chain interactions as well as contacts with solvent molecules, whether it be detergents, denaturants, stabilizing salts and osmolytes or lipids. Ultimately we hope this will lead to a greater manipulative ability vis-a-vis processes of both basic, pharmaceutical and industrial relevance. The general approach is to use available spectroscopic techniques (fluorescence, CD, stopped-flow, FTIR, NMR and dynamic and static light scattering) to generate data which can be analyzed in a quantitative manner to develop models and mechanisms for conformational changes at the molecular level.  

Protein detergent interactions
Protein fibrillation
Membrane proteins