The specific aim of the proposed research is to characterize the structural and electronic properties of the active pigments in energy transducing proteins. The bacterial photosynthetic reaction center (RC) has been chosen for study because this class of proteins represents a prototypical model system for investigating the properties that facilitate fast electron transfer over distances on the order of the width of the biological membrane. In addition, the RC is the only integral membrane protein for which the macromolecular arrangement of the active pigments in the protein matrix is known. The principal investigative tool that will be used is resonance Raman (RR) spectroscopy. The first objective is to characterize the UV-vis-excitation (ca. 350-700 nm) RR spectra of the bacterochlorphyll (BChl) and bacteriopheophytin (BPh) pigments is RCs from Rb. sphaeroides, Rb. capsulatus and Rps. viridis wild-type. The goal of these studies is to examine the individual BChl and BPh molecules with as much selectivity as possible in order to assess the structural similarities and/or differences between the various pigments in RCs from a given species and between RCs from different species. The second objective is to characterize the UV- vis-excitation RR spectra of a number of genetically modified RCs from Rb. capsulatus. These studies will focus on systems in which genetic modifications have been made in the amino acid residues in the vicinity of the primary electron donor and acceptor and also the accessory BChls. These studies will be conducted in parallel with those on the wild-type systems in order to assess the structural consequences of the various site- specific mutations. The third objective is to probe the red-most, Qy absorptions (ca. 750-1000 nm) of the BChls and BPhs by using RR techniques. The red-most band of the primary donor (ca. 850-1000 nm) will be the focal point of the near-infrared (NIR) RR studies. The goal of these studies is to characterize the vibrational and electronic properties of the lowest- energy electronic states. The fourth objective is to obtain NIR-excitation RR spectra of RCs in which genetical modifications have been made in the vicinity of the photophysically active pigments. The goal of these studies is to determine how modifications in specific amino acids influence the vibrational and electronic properties of the electron-donating excited state of RCs.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM039781-06
Application #
2180028
Study Section
Biophysical Chemistry Study Section (BBCB)
Project Start
1988-07-01
Project End
1996-06-30
Budget Start
1994-07-01
Budget End
1995-06-30
Support Year
6
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of California Riverside
Department
Chemistry
Type
Schools of Earth Sciences/Natur
DUNS #
City
Riverside
State
CA
Country
United States
Zip Code
92521
Czarnecki, Kazimierz; Chen, Lei; Diers, James R et al. (2006) Low-frequency resonance Raman studies of the H(M202)G cavity mutant of bacterial photosynthetic reaction centers. Photosynth Res 88:31-41
Pendon, Zeus D; Sullivan, James O; van der Hoef, Ineke et al. (2005) Stereoisomers of carotenoids: spectroscopic properties of locked and unlocked cis-isomers of spheroidene. Photosynth Res 86:5-24
Tracewell, Cara A; Cua, Agnes; Bocian, David F et al. (2005) Resonance Raman spectroscopy of carotenoids in Photosystem II core complexes. Photosynth Res 83:45-52
Chen, Lei; Kirmaier, Christine; Holten, Dewey et al. (2005) Resonance Raman characterization of Rhodobacter capsulatus reaction centers with lysine mutations near the accessory bacteriochlorophylls. Photosynth Res 83:35-43
Cua, Agnes; Vrettos, John S; de Paula, Julio C et al. (2003) Raman spectra and normal coordinate analyses of low-frequency vibrations of oxo-bridged manganese complexes. J Biol Inorg Chem 8:439-51
Tracewell, C A; Cua, A; Stewart, D H et al. (2001) Characterization of carotenoid and chlorophyll photooxidation in photosystem II. Biochemistry 40:193-203
Czarnecki, K; Cua, A; Kirmaier, C et al. (1999) Relationship between altered structure and photochemistry in mutant reaction centers in which bacteriochlorophyll replaces the photoactive bacteriopheophytin. Biospectroscopy 5:346-57
Stewart, D H; Cua, A; Chisholm, D A et al. (1998) Identification of histidine 118 in the D1 polypeptide of photosystem II as the axial ligand to chlorophyll Z. Biochemistry 37:10040-6
Cua, A; Kirmaier, C; Holten, D et al. (1998) Resonance raman characterization of reaction centers with an Asp residue near the photoactive bacteriopheophytin. Biochemistry 37:6394-401
Czarnecki, K; Schenck, C C; Bocian, D F (1997) Resonance Raman characterization of reaction centers in which bacteriochlorophyll replaces the photoactive bacteriopheophytin. Biochemistry 36:14697-704

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