This proposal aims to develop a structurally based model of carotenoid participation in light harvesting and photoprotection in vivo. He isolates, purifies, reconstitutes, exchanges pigments in, crystallizes and genetically modifies bacterial reaction center and antenna complexes. He uses tools such as X-ray diffraction, NMR, and Raman spectroscopy to examine structures directly and also employs EPR and optical spectroscopy.
The aim i s to determine the structure of carotenoids as they occur in these photosynthetic units, to generate a complete understanding of the relationship between the spectroscopic signatures and structures of the carotenoids and to discover the relations between these structures and the specific roles of the carotenoids in light harvesting and photoprotection. The data are expected to provide a basis from which to understand more complex systems; e.g. higher plant pigment-protein complexes whose properties are more complex than the bacterial systems.
The specific aims of the proposal are: (1) To examine the structures of carotenoids in photosynthetic pigment protein complexes; (2) To explore the relationships between the carotenoid structures and their spectroscopic properties; (3) To determine the relationships between the carotenoid structures and their mechanisms of light-harvesting and photoprotection.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Molecular and Cellular Biophysics Study Section (BBCA)
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University of Connecticut
Schools of Arts and Sciences
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Polivka, Tomas; Frank, Harry A (2010) Molecular factors controlling photosynthetic light harvesting by carotenoids. Acc Chem Res 43:1125-34
Cai, Jianfeng; Niedzwiedzki, Dariusz M; Frank, Harry A et al. (2010) Ultrafast energy transfer within pyropheophorbide-a tethered to self-assembling DNA quadruplex. Chem Commun (Camb) 46:544-6
Niedzwiedzki, Dariusz M; Enriquez, Miriam M; Lafountain, Amy M et al. (2010) Ultrafast Time-resolved Absorption Spectroscopy of Geometric Isomers of Xanthophylls. Chem Phys 373:80-89
Schulte, Tim; Niedzwiedzki, Dariusz M; Birge, Robert R et al. (2009) Identification of a single peridinin sensing Chl-a excitation in reconstituted PCP by crystallography and spectroscopy. Proc Natl Acad Sci U S A 106:20764-9
Kajikawa, Takayuki; Aoki, Kazuyoshi; Singh, Ram Shanker et al. (2009) Syntheses of allene-modified derivatives of peridinin toward elucidation of the effective role of the allene function in high energy transfer efficiencies in photosynthesis. Org Biomol Chem 7:3723-33
Ryppa, Claudia; Niedzwiedzki, Dariusz; Morozowich, Nicole L et al. (2009) Stepwise conversion of two pyrrole moieties of octaethylporphyrin to pyridin-3-ones: synthesis, mass spectral, and photophysical properties of mono and bis(oxypyri)porphyrins. Chemistry 15:5749-62
Niedzwiedzki, Dariusz M; Sandberg, Daniel J; Cong, Hong et al. (2009) Ultrafast time-resolved absorption spectroscopy of geometric isomers of carotenoids. Chem Phys 357:4
Niedzwiedzki, Dariusz M; Chatterjee, Nirmalya; Enriquez, Miriam M et al. (2009) Spectroscopic investigation of peridinin analogues having different pi-electron conjugated chain lengths: exploring the nature of the intramolecular charge transfer state. J Phys Chem B 113:13604-12
Niedzwiedzki, Dariusz M; Sandberg, Daniel J; Cong, Hong et al. (2009) Ultrafast Time-resolved Absorption Spectroscopy of Geometric Isomers of Carotenoids. Chem Phys 357:4-16
Chatterjee, Nirmalya; Niedzwiedzki, Dariusz M; Aoki, Kazuyoshi et al. (2009) Effect of structural modifications on the spectroscopic properties and dynamics of the excited states of peridinin. Arch Biochem Biophys 483:146-55

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