Strukturelle Dynamik von photosensitiven Proteinen
Strukturelle Dynamik von photosensitiven Proteinen
The thesis presented here describes the application of intense, pulsed X-rays from a synchrotron to the investigation of biochemical reactions triggered by light. The workincludes contributions to the instrumentation of a beamline and experiments with the proteins myoglobin, the photoactive yellow p...
Saved in:
Personal Name(s): | Schotte, Friedrich (Corresponding author) |
---|---|
Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2000
|
Physical Description: |
117 p. |
Document Type: |
Report Book |
Research Program: |
ohne Topic |
Series Title: |
Berichte des Forschungszentrums Jülich
3790 |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
The thesis presented here describes the application of intense, pulsed X-rays from a synchrotron to the investigation of biochemical reactions triggered by light. The workincludes contributions to the instrumentation of a beamline and experiments with the proteins myoglobin, the photoactive yellow protein (PYP) and bacteriorhodopsin.The instrumentational work led to an improvement of the time resolution for pulsed Laue experiments from 10 ns to 100 ps. My contribution was the integration of three majornew components, a femtosecond laser system, a fast X-ray chopper and a heatload x-ray shutter, into the beamline control system. For laser/X-ray pump probe experiments, thetime delay can now be tuned under software control with picosecond precision. As a diagnostic to verify the photo-excitation of samples, I constructed a microsecond timeresolvedspectrometer with micro-focusing capabilities, which can measure the excitation degree of a sample online or offline. As part of an external collaboration, I contributed tothe construction of a ferntosecond time-resolved offline spectrometer. It was built to answer the question whether protein crystals can be excited with a focused femtosecondlaser to a sufficiently high degree without damage, and to identify the optimal triggering conditions.The laser triggering studies showed in the case of myoglobin that a protein crystal can be excited with ferntosecond laser pulses without disordering the crystalline structure orroducing photochemical damage. 100-ps time resolved Laue diffraction experiments on Myoglobin-CO show structural dynamics compatible with earlier nanosecondexperiments, but no clear indication for a CO docking site. A nanosecond time-resolved Laue experiment on PYP showed an early photocycle intermediate, with a photoisomerizedchromophore but little larger rearrangement in the protein. Although technically successful 100-ps time-resolved Laue diffraction experiments on PYP havebeen repeated several times, they have not yet given structural results. In the case of bacteriorhodopsin purple membrane, time-resolved powder diffraction with a choppedmonochromatic X-ray beam was used, accumulating thousands of images on the detector. In this way a millisecond time-resolved electron difference map for the wild-type M statewas obtained. The myoglobin and PYP experiments were collaborations with external workgroups. |