Type
Text
Type
Dissertation
Advisor
Tonge, Peter | London, Erwin | Scharer, Orlando | Bowen, Mark.
Date
2013-12-01
Keywords
Chemistry | AppA, BLUF, Infrared, Time resolved
Department
Department of Chemistry.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/77093
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Femtosecond (fs) excitation of photoreceptors results in protein structural changes that occur on the microsecond to millisecond timescale or longer. It is thus of fundamental interest to understand how these fast timescale events dictate large scale protein dynamics that occur on much longer (106 orders of magnitude) timescales. AppA is a blue light using FAD (BLUF) protein which acts as a transcriptional antirepressor in Rhodobacter sphaeroides. The ultrafast photocycle and IR spectra are well characterized and involve a near instantaneous (<100 fs) response of the protein matrix that surrounds the chromophore. While there has been extensive study on the ultrafast time scales there has never been an observation of the kinetics of the light induced structural changes in the protein. Here we investigated the ultrafast (ps) to ms structural dynamics through transient IR. The data show that significant structural changes occur on the sub microsecond timescale following photoactivation. In addition our work has expanded to other BLUF proteins. BlsA is a BLUF protein found in the pathogenic bacterium Acinetobacter baumannii. Vibrational data together with homology modeling identify significant differences in β 5 strand caused by photoactivation, a region of BLUF photoreceptors proposed to be essential for signal modulation, that are unique for BlsA. In addition, the BLUF protein PixD, from Synechocystis, was characterized by transient IR, where photoexcitation results in radical pair formation, an event not observed in AppA. Transient IR also revealed that light state formation is complete within nanoseconds for PixD, suggesting a unique mechanism for single and multidomain BLUF systems. | 254 pages
Recommended Citation
Brust, Richard James, "Molecular Movie Magic: Real-time Picosecond to Microsecond Structural Dynamics of Photoactive Flavoproteins" (2013). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2930.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2930