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Extended Förster theory for determining intraprotein distances: 1. The K2-dynamics and fluorophore reorientation
Umeå University, Faculty of Science and Technology, Chemistry.
Umeå University, Faculty of Science and Technology, Chemistry. Umeå University, Faculty of Science and Technology, Chemistry.
Umeå University, Faculty of Science and Technology, Chemistry.
Umeå University, Faculty of Science and Technology, Chemistry.
2004 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 44, 17243-17250 p.Article in journal (Refereed) Published
Abstract [en]

A detailed analysis of the previously developed (J. Chem. Phys. 1996, 105, 10896) extended Förster theory (EFT) is presented for analyzing electronic energy migration within pairs of donors (D). Synthetic data that mimics experimental time-correlated single photon counting data were generated and re-analyzed. To cover a wide dynamic range and various orientational restrictions, the rates of reorientation, as well as the orientational configurations of the interacting D-groups were varied. In general DD distances are recovered within an error limit of 5%, while the errors in orientational configurations are usually larger. The Maier−Saupe and cone potentials were used to generate an immense variety of orientational trajectories. The results obtained exhibit no significant dependence on the choice of potential function used for generating EFT data. Present work demonstrates how to overcome the classical “κ2-problem” and the frequently applied approximation of κ2 = 2/3 in the data analyses. This study also outlines the procedure for analyzing fluorescence depolarization data obtained for proteins, which are specifically labeled with D-groups. The EFT presented here brings the analyses of DDEM data to the same level of molecular detail as in ESR- and NMR-spectroscopy.

Place, publisher, year, edition, pages
2004. Vol. 108, no 44, 17243-17250 p.
Keyword [en]
Thimerosal, Ethylmercury, Mice, Autoimmunity
Identifiers
URN: urn:nbn:se:umu:diva-2134DOI: 10.1021/jp040423dOAI: oai:DiVA.org:umu-2134DiVA: diva2:139964
Available from: 2007-02-15 Created: 2007-02-15 Last updated: 2017-12-14Bibliographically approved
In thesis
1. On the quantitative analysis of electronic energy transfer/migration in proteins studied by fluorescence spectroscopy
Open this publication in new window or tab >>On the quantitative analysis of electronic energy transfer/migration in proteins studied by fluorescence spectroscopy
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Two recently developed theories of electronic energy transfer/migration were for the first time applied to real protein systems for extracting molecular distances. The partial donor-donor energy migration (PDDEM) is an extension to the previously developed donor-donor energy migration (DDEM, F Bergström et al PNAS 96, 1999, 12477) which allows using chemically identical but photophysically different fluorophores in energy migration experiments. A method based on fluorescence quenching was investigated and applied to create an asymmetric energy migration between fluorophores which were covalently and specifically attached to plasminogen activator inhibitor type 2 (PAI-2). It was also shown experimentally that distance information can be obtained if the fluorescence relaxation for photophysically identical donors, exhibits multi-exponential relaxation.

An extended Förster theory (EFT) that was previously derived (L. B.-Å. Johansson et al J. Chem. Phys., 1996, 105) ha been developed for analysis of donor-acceptor energy transfer systems as well as DDEM systems. Recently the EFT was also applied to determine intra molecular distances in the protein plasminogen activator inhibitor type 1 (PAI-1) which was labelled with a sulfhydryl specific derivative of BODIPY. The EFT explicitly accounts for the time-dependent reorientations which in a complex manner influence the rate of electronic energy transfer/migration. This difficulty is related to the “k2-problem”, which has been solved. It is also shown experimentally that the time-correlated single-photon counting (TCSPC) data is sensitive to the mutual configuration between the interacting fluorophores. To increase the accuracy in the extracted parameters it is furthermore suggested to collect the fluorescence data under various physico-chemical conditions. It was also shown that the Förster theory is only valid in the initial part of the fluorescence decay.

Place, publisher, year, edition, pages
Umeå: Kemi, 2007. 46 p.
Keyword
Biophysical Chemistry
National Category
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-1009 (URN)978-91-7264-263-8 (ISBN)
Public defence
2007-03-02, KBC3A9, KBC-huset, 901 87, Umeå, 10:30 (English)
Opponent
Supervisors
Available from: 2007-02-15 Created: 2007-02-15 Last updated: 2009-10-28Bibliographically approved
2. Simulation of Relaxation Processes in Fluorescence, EPR and NMR Spectroscopy
Open this publication in new window or tab >>Simulation of Relaxation Processes in Fluorescence, EPR and NMR Spectroscopy
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Simulering av Relaxationsprocesser inom Fluoresens, EPR och NMR Spektroskopi
Abstract [en]

Relaxation models are developed using numerical solutions of the Stochastic Liouville Equation of motion. Simplified descriptions such as the stochastic master equation is described in the context of fluorescence depolarisation experiments. Redfield theory is used in order to describe NMR relaxation in bicontinuous phases. The stochastic fluctuations in the relaxation models are accounted for using Brownian Dynamics simulation technique. A novel approach to quantitatively analyse fluorescence depolarisation experiments and to determine intramolecular distances is presented. A new Brownian Dynamics simulation technique is developed in order to characterize translational diffusion along the water lipid interface of bicontinuous cubic phases.

Place, publisher, year, edition, pages
Umeå: Kemi, 2004. 34 p.
Keyword
Physical chemistry, EPR, NMR, Energy migration, bicontinuous cubic phase, Stochastic Liouville Equation, Brownian Dynamics, Fysikalisk kemi
National Category
Physical Chemistry
Research subject
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-244 (URN)91-7305-666-9 (ISBN)
Public defence
2004-05-14, KB3A9, KBC, Biofysikalisk kemi, Umeå Universitet, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2004-04-22 Created: 2004-04-22 Last updated: 2009-10-26Bibliographically approved

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