Bridgette Barry Professor Senior Editor, Journal of Physical Chemistry Office: IBB 3311 Phone: 404-385-6085 Fax: 404-894-2295 E-mail Bridgette Barry Research Group Web site Georgia Tech Molecular Biophysics Georgia Tech Structural Biology

A.B., Oberlin College, 1978; Ph.D., University of California, Berkeley, 1984; NIH and McKnight Postdoctoral Fellow, Michigan State University, 1985-1988

AAAS Fellow, 2008; WISE Lectureship, University of Minnesota, 2001; Edna Roe Lectureship, International Union of Photobiology, 2000; National Honorary Member, Iota Sigma Pi, 1999; Career Advancement Award, National Science Foundation, 1997; Bush Sabbatical Award, University of Minnesota, 1997; McKnight-Land Grant Professor, University of Minnesota, 1990-1993

RESEARCH INTERESTS - Molecular Biophysics, Membrane Biochemistry, Photosynthesis

TECHNIQUES - Infrared Spectroscopy, Raman Spectroscopy, EPR Spectroscopy, Mass Spectrometry

Proton coupled electron transfer in photosynthesis, DNA synthesis, and model peptide maquettes.  Long distance electron transfer plays an important role in many biological processes, including photosynthesis, oxidative phosphorylation, and DNA synthesis.  In these reactions, radical transport may occur and may involve transfer of an electron alone (ET) or a proton coupled, electron transfer reaction (PET). The mechanism by which the protein environment controls these reactions is just beginning to be elucidated.  Aromatic amino acids, such as tyrosine and tryptophan, can play key roles in facilitating these processes.  In my laboratory, we are using FT-IR, Raman, transient infrared, and EPR spectroscopy to elucidate how non-covalent interactions control the function of redox-active tyrosine residues.  We are studying ribonucleotide reductase (RNR) and photosystem II (PSII).  PSII carries out the light-induced oxidation of water and the production of molecular oxygen.  PSII provides a prototypical system to study redox active amino acids, because PSII contains two redox-active tyrosines with different midpoint potentials and different reduction kinetics.  Further, PSII provides a kinetically tractable light-inducible system, in which electron transfer reactions can be initiated by a laser flash.  RNR catalyzes the reduction of ribonucleotides to deoxynucleotides.  In E. coli RNR, a redox-active tyrosine is proposed to be a radical initiator in this reaction.  A more detailed understanding of mechanism in RNR will identify new targets for anti-cancer therapies. We are also designing and studying beta hairpin peptides, which contain an oxidizable tyrosine.  These de novo, biomimetic peptides are being used to test hypotheses generated from studies of the natural systems.

Post-translational modifications in membrane proteins. Amino acid side chains in proteins can be modified during or after the synthesis of the protein. The modified amino acid may have unique reactivity or may provide a cellular signal. My group is using mass spectrometry and peptide mapping to identify novel, modified amino acids in PSII.  PSII consists both of integral, membrane-spanning subunits and of extrinsic subunits.  Some of the modified amino acids are located on integral membrane proteins, near the active site for water oxidation.  These unique amino acids may play a role in the structure and function of the enzyme.  Other PSII modifications may be important in signaling for the turnover or degradation of the enzyme inside the cell. 

Oxygen production  in photosynthesis.   My laboratory is studying the mechanism of water oxidation in photosynthesis.  The oxygen produced from this reaction is responsible for the maintenance of aerobic life on earth.  The reactions occur at the oxygen-evolving complex (OEC) of PSII.  The OEC contains a tetranuclear manganese cluster and accumulates the four oxidizing equivalents necessary for oxygen production from water.  The sequentially oxidized forms of the catalytic site are called the S states, where n refers to the number of oxidizing equivalents stored on the OEC.  Chloride and calcium play important, but not completely understood, roles in the S state cycle. We are identifying protein structural changes important in catalysis, using transient infrared and FT-IR spectroscopy.  We are using metal exchange to gain new insight into the role of calcium and chloride, and we are studying the role of extrinsic PSII subunits in proton transfer reactions.  Laser flashes can be used to step through the S state cycle and to characterize each chemical intermediate.  For complex membrane proteins, such as PSII, vibrational spectroscopic methods, such as transient infrared and FT-IR spectroscopy, provide an ideal method to identify catalysis-linked structural changes, to monitor kinetics, and to assess the importance of protein dynamics in enzymatic turnover.

 

Recent Publications