Laboratory of Biophysics
W. Ostwaldi 1, 50411 Tartu D wing, 1st floor Staff contacts |
We are investigating how natural or genetically modified photosynthetic pigment-protein complexes extracted from bacteria operate, what is the interplay between their structure and function, and how external conditions such as temperature, pressure and the composition of the host solution modify their properties and functioning. A good example is the peripheral light-harvesting complex LH2 of the photosynthetic purple bacterium Rhodopseudomonas acidophila shown on the picture above. Owing to a special manifold of energy levels this complex is very efficient in harvesting and transferring the energy of the absorbed sunlight.
In experimental studies, we utilize various spectroscopic methods, which cover a broad spectral range from ultraviolet (protein spectra) to near-infrared (pigment spectra). Apart form absorption, fluorescence and circular dichroism spectroscopies combined with microscopy if needed we also use several laser-based methods as high-resolution selective spectroscopy and picosecond time-resolved spectroscopy. A diamond anvil cell enables to apply a hydrostatic pressure up to 50 kbar and a helium cryostat enables to cool the sample down to 10 K.
Experimental results are interpreted by using models of energy flow kinetics and by molecular dynamics and quantum chemical calculations.
Another research topics is the neutron scattering of biological samples based on international collaboration taking advantage of the European Spallation Source and other neutron sources.
The complexity of preparing the samples of pigment-protein complexes and their inherent instability and variability calls for an active teamwork with other laboratories providing us with the samples. Our cooperation partners can be found in USA, Australia, Netherlands, China, Lithuania, France, Sweden, UK, Germany, Russia, Ukraine, and elsewhere.
Our more detailed webpage can be found at utbiophys.eu
Projects
- Team grant "New Insights into Photosynthetic Excitations Enabled by High-pressure Perturbation Spectroscopy" (2020-2024) PRG664 Arvi Freiberg
- Team grant "Functionally relevant protein structure and dynamics studied by neutron scattering" (2019−2023) PRG539 Jörg Pieper
- Start-up grant "Energy transfer in the photosynthetic unit of green sulphur bacterium" (2019−2022) PSG264 Juha Matti Linnanto
- Research Infrastructures Roadmap support "Estonian participation in designing, construction and application of the ESS" (09.2015−08.2022) SLTKT16432T Enn Lust
Selected publications
- E. Jalviste; K. Timpmann; M. Chenchiliyan; L. Kangur; M. R. Jones; A. Freiberg (2020). "High-Pressure Modulation of Primary Photosynthetic Reactions." The Journal of Physical Chemistry B, 124 (5), 718−726.
- K. Timpmann; E. Jalviste; M. Chenchiliyan; L. Kangur; M.R. Jones; A. Freiberg (2020). "High-pressure tuning of primary photochemistry in bacterial photosynthesis: membrane-bound versus detergent-isolated reaction centers." Photosynthesis Research, 144, 209–220
- L. Kangur; M. Rätsep; K. Timpmann; Z.-Y. Wang-Otomo; A. Freiberg (2020). "The two light-harvesting membrane chromoproteins of Thermochromatium tepidum expose distinct robustness against temperature and pressure." Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1861 (8), 148205.
- L. Kangur; K. Timpmann; D. Zeller; P. Masson; J. Peters; A. Freiberg (2019). "Structural stability of human butyrylcholinesterase under high hydrostatic pressure." Biochimica et Biophysica Acta - Proteins and Proteomics, 1867 (2), 107−113.
- M. Golub; J. Pieper; J. Peters; L. Kangur; E.C. Martin; C.N. Hunter; A. Freiberg, (2019). "Picosecond Dynamical Response to a Pressure-Induced Break of the Tertiary Structure Hydrogen Bonds in a Membrane Chromoprotein." The Journal of Physical Chemistry B, 123, 2087−2093.
- M. Rätsep; J.M. Linnanto; A. Freiberg (2019). "Higher Order Vibronic Sidebands of Chlorophyll a and Bacteriochlorophyll a for Enhanced Excitation Energy Transfer and Light Harvesting." The Journal of Physical Chemistry B, 123 (33), 7149−7156.
- M. Pajusalu; M. Rätsep; L. Kangur; A. Freiberg (2019). "High-pressure control of photosynthetic excitons." Chemical Physics, 525, 110404
- K. Leiger; J.M. Linnanto; M. Rätsep; K. Timpmann; A.A. Ashikhmin; A.A. Moskalenko; T.Y. Fufina; A.G. Gabdulkhakov; A. Freiberg (2019). "Controlling Photosynthetic Excitons by Selective Pigment Photooxidation." The Journal of Physical Chemistry B, 123 (1), 29−38.
- M. Rätsep; J.M. Linnanto; R. Muru; M. Biczysko; J.R. Reimers; A. Freiberg (2019). "Absorption-emission symmetry breaking and the different origins of vibrational structures of the 1Qy and 1Qx electronic transitions of pheophytin a." Journal of Chemical Physics, 151 (16), 165102.
- M. Golub; M. Moldenhauer; F.-J. Schmitt; A. Feoktystov, Artem; H. Mändar; E. Maksimov; T. Friedrich; J. Pieper (2019). "Solution Structure and Conformational Flexibility in the Active State of the Orange Carotenoid Protein: Part I. Small-Angle Scattering." The Journal of Physical Chemistry B, 123 (45), 9525−9535.
People
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Arvi Freiberg |
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Jörg Pieper |
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Juha Matti Linnanto |
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Margus Rätsep |
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Kõu Timpmann |
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Maksym Golub |
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Erko Jalviste |
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Liina Kangur |
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Kristjan Leiger |
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Silja Erg |
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Alexandra Lehtmets |
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Helis Paas |
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Pavina Salabeea |