A5084605682- Photosynthetic Processes and Mechanisms
- Spectroscopy and Quantum Chemical Studies
- Metal complexes synthesis and properties
- Catalysis and Oxidation Reactions
- DNA and Nucleic Acid Chemistry
- Electrochemical Analysis and Applications
- Mass Spectrometry Techniques and Applications
- Various Chemistry Research Topics
- RNA and protein synthesis mechanisms
- CO2 Reduction Techniques and Catalysts
- Injury Epidemiology and Prevention
- X-ray Spectroscopy and Fluorescence Analysis
- Metal-Catalyzed Oxygenation Mechanisms
- Photoreceptor and optogenetics research
- Membrane Separation and Gas Transport
- Burn Injury Management and Outcomes
- Redox biology and oxidative stress
- Fire Detection and Safety Systems
- Radiopharmaceutical Chemistry and Applications
- Air Quality Monitoring and Forecasting
- Ferrocene Chemistry and Applications
- Pharmaceutical Practices and Patient Outcomes
- Medication Adherence and Compliance
- Lanthanide and Transition Metal Complexes
- Advanced biosensing and bioanalysis techniques
Willamette University
2008-2022
Action for Children
2013
Lawrence Berkeley National Laboratory
1998-2004
University of California, Berkeley
2001-2004
University of California, Davis
2001
University of California, Santa Barbara
1997-1998
Friedrich-Alexander-Universität Erlangen-Nürnberg
1998
A key question for the understanding of photosynthetic water oxidation is whether four oxidizing equivalents necessary to oxidize dioxygen are accumulated on Mn ions oxygen-evolving complex (OEC), or some ligand-centered oxidations take place before formation and release during S(3) --> [S(4)] S(0) transition. Progress in instrumentation flash sample preparation allowed us apply Kbeta X-ray emission spectroscopy (Kbeta XES) this problem first time. The XES results, combination with...
A key component required for an understanding of the mechanism evolution molecular oxygen by photosynthetic oxygen-evolving complex (OEC) in photosystem II (PS II) is knowledge structures Mn cluster OEC each its intermediate redox states, or S-states. In this paper, we report first detailed structural characterization using extended X-ray absorption fine structure (EXAFS) spectroscopy S0 state, which exists immediately after release oxygen. On basis EXAFS spectroscopic results, most likely...
The proximity of Ca to the Mn cluster photosynthetic water-oxidation complex is demonstrated by X-ray absorption spectroscopy. We have collected EXAFS data at K-edge using active PS II membrane samples that contain approximately 2 per 4 Mn. These are much less perturbed than previously investigated Sr-substituted samples, which were prepared after depletion. new clearly shows backscattering from 3.4 Å, a distance agrees with surmised recorded EXAFS. This result also consistent earlier...
The oxygen-evolving complex of photosystem II (PS II) in green plants and algae contains a cluster four Mn atoms the active site, which catalyzes photoinduced oxidation water to dioxygen. Along with Mn, calcium chloride ions are necessary cofactors for proper functioning complex. current study using polarized Sr EXAFS on oriented Sr-reactivated samples shows that Fourier peak II, fits best at 3.5 Å rather than lighter (C, N, O, or Cl), is dichroic, larger magnitude 10° (angle between PS...
Abstract We have developed a multiweek laboratory project in which students isolate myoglobin and characterize its structure, function, redox state. The important techniques covered this include size‐exclusion chromatography, electrophoresis, spectrophotometric titration, FTIR spectroscopy. Regarding protein work with computer modeling visualization of homologues, after they spectroscopically thermal denaturation. Students also study function (ligand binding equilibrium) are instructed on...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProbing Changes in the Conformation of tRNAPhe: An Integrated Biochemistry Laboratory CourseSarah R. Kirk , Todd P. Silverstein Karen L. McFarlane Holman and Buck H. Taylor View Author Information Department Chemistry, Willamette University, Salem, OR 97301Cite this: J. Chem. Educ. 2008, 85, 5, 666Publication Date (Web):May 1, 2008Publication History Received3 August 2009Published online1 May 2008Published inissue 1...
Time-resolved infrared and time-resolved optical spectroscopy have been used to probe further into the spectra dynamics of reactive intermediates I Iind generated by flash photodecarbonylation respective acetyl complexes CpFe(CO)2(C(O)CH3) (A) IndFe(CO)2(C(O)CH3) (Aind) (Cp = η5-C5H5; Ind η5-C9H7). The competitive reaction CH3 migration metal, trapping CO, other ligands such as P(OCH3)3 were determined for these in various solvents. Hydrostatic pressure effects on photoreaction pathways both...
The transient formed by the photolysis of methyl complex CpFe(CO)2CH3 (M, Cp = (η5-C5H5)) has been studied FTIR spectroscopy in methylcyclohexane solution at 77 K and time-resolved infrared detection ambient-temperature solutions cyclohexane tetrahydrofuran. IR spectrum intermediate IM displays a single νco absorption band can be characterized as monocarbonyl. In 295 solution, reaction with CO occurs second-order kinetics (rate kco[IM][CO]) kco values (6.3 ± 0.2) × 108 (3.4 0.4) 106 M-1 s-1...
X-ray Absorption Spectroscopy (XAS) is a powerful tool to investigate sulfur in biological molecules. The spectral features are sensitive the local electronic and geometric environment of atom; thus, they constitute fingerprint different chemical forms which present. This allows straightforward detection ratio between free thiols disulfides. Intra- or inter-molecular disulfide bond formation residues plays an important role structural conformational changes proteins, such can be investigated...
Mo L-edge and S K-edge X-ray absorption spectroscopy were applied to investigate the charge distribution between in a series of thiolate compounds, which serve as amide-sulfur H-bonding models exhibit different redox potentials arising from polar group effects ligand hydrogen bonds near center. For all oxidized complexes, spectra thiolate-based pre-edge feature centered at 2470.2 eV inflection point oCCurs 2472.0 eV. No intense is observed for reduced model compounds energy shift position...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFluorescence Spectroscopy of tRNAPhe Y Base in the Presence Mg2+ and Small Molecule LigandsSarah R. Kirk , Todd P. Silverstein Karen L. McFarlane Holman View Author Information Department Chemistry, Willamette University, Salem, OR 97301Cite this: J. Chem. Educ. 2008, 85, 5, 678Publication Date (Web):May 1, 2008Publication History Received3 August 2009Published online1 May 2008Published inissue 1...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUV Thermal Melting Curves of tRNAPhe in the Presence LigandsSarah R. Kirk , Todd P. Silverstein and Karen L. McFarlane Holman View Author Information Department Chemistry, Willamette University, Salem, OR 97301Cite this: J. Chem. Educ. 2008, 85, 5, 674Publication Date (Web):May 1, 2008Publication History Received3 August 2009Published online1 May 2008Published inissue 1...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal-Catalyzed Cleavage of tRNAPheSarah R. Kirk , Todd P. Silverstein and Karen L. McFarlane Holman View Author Information Department Chemistry, Willamette University, Salem, OR 97301Cite this: J. Chem. Educ. 2008, 85, 5, 676Publication Date (Web):May 1, 2008Publication History Received3 August 2009Published online1 May 2008Published inissue 1 2008https://pubs.acs.org/doi/10.1021/ed085p676https://doi.org/10.1021/ed085p676research-articleACS...
Calcium and chloride are necessary cofactors for the proper function of oxygen-evolving complex (OEC) Photosystem II (PS II). Located in thylakoid membranes green plants, cyanobacteria algae, PS OEC catalyze light-driven oxidation water into dioxygen (released biosphere), protons electrons carbon fixation. The actual chemistry is performed by a cluster four manganese atoms, along with requisite Ca{sup 2+} Cl{sup -}. While Mn has been extensively studied X-ray absorption techniques,...