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29 results on '"Sjodin, Theodore"'

1. Proximal and distal influences on ligand binding kinetics in microperoxidase and heme model compounds

Author

Wenxiang Cao, Xiong Ye, Georgiev, Georgi Y., Berezhna, Svitlana, Sjodin, Theodore, Champion, Paul M., Sage, J. Timothy, Wei Wang, and Demidov, Andrey A.

Subjects
Carbon monoxide -- Chemical properties, Raman spectroscopy -- Usage, Photolysis -- Methods, Biological sciences, Chemistry
Abstract

The proximal and distal influences on ligand rebinding kinetics are analyzed by using laser flash photolysis and time-resolved Raman spectroscopy of CO-bound heme complexes. It is noticed that perturbations of the proximal heme ligand, which are associated with intermolecular interactions, are strongly correlated with the dramatic aggregation-dependent changes observed in the ligand rebinding kinetics.

Published
2004

2. Determination of the complete set of iron normal modes in the Heme model compound Fe(super III) (OEP)CI from nuclear resonance vibrational spectroscopic data

Author

Budarz, Timo E., Sturhahn, Wolfgang, Alp, Ercan E., Prohofsky, E.W., Durbin, Stephen M., Sjodin, Theodore, and Sage, Timothy J.

Subjects
Hemoproteins -- Observations, Iron compounds -- Observations, Vibrational spectra -- Methods, Chemicals, plastics and rubber industries
Abstract

An investigation of the model compound chloro iron octaphenylporphyrin Fe(OEP)Cl, as a stepin understanding biologically significant dynamics in heme proteins is reported. A normal-mode analysis is employed to calculate the Fe(super 57) partial vibrational density of states (VDOS) and refined to absorption data from nuclear resonance vibrational spectroscopy.

Published
2003

3. Investigations of anharmonic low-frequency oscillations in heme proteins

Author

Rosca, Florin, Kumar, Anad T. N., Ionascu, Dan, Ye, Xiong, Demidov, Andrey A., Sjodin, Theodore, Wharton, David, Barrick, Douglas, Sligar, Stephen G., Yonetani, Takashi, and Champion, Paul M.

Subjects
Chemistry, Physical and theoretical -- Research, Hemoproteins -- Physiological aspects, Oscillation -- Physiological aspects, Photochemical research -- Analysis, Absorption -- Physiological aspects, Chemicals, plastics and rubber industries
Published
2002

4. Resonance Raman and EPR investigations of the D251N oxycytochrome P450 (sub)cam/putidaredoxin complex

Author

Sjodin, Theodore, Christian, James F., Macdonald, Iain D.G., Davydov, Roman, Unno, Masashi, Sligar, Stephen G., Hoffman, Brian M., and Champion, Paul M.

Subjects
Biochemistry -- Research, Raman spectroscopy -- Usage, Electron paramagnetic resonance -- Usage, Cytochromes -- Research, Protons -- Research, Biological sciences, Chemistry
Abstract

Research has been conducted on the dioxygen bound state of cytochrome P450 (sub)cam mutant. The results of the resonance Raman and electronic paramagnetic resonance studies of this mutant and its complex with reduced putidaredoxin are discussed.

Published
2001

5. Femtosecond multicolor pump: probe spectroscopy of ferrous cytochrome c

Author

Wang, Wei, Demidov, Andrey A., Rosca, Florin, Sjodin, Theodore, Sheeran, Mariel, Champion, Paul M., Cao, WenXiang, and Ye, Xiong

Subjects
Cytochrome c -- Research, Cytochrome c -- Optical properties, Cytochrome c -- Chemical properties, Laser spectroscopy -- Usage, Chemistry, Physical and theoretical -- Research, Chemicals, plastics and rubber industries
Abstract

Cytochrome c (cyt c) is a member of the ubiquitous class of heme proteins, which function as reversible redox carriers in electron-transport chains. Ligand photolysis and subsequent electronic and structural relaxation, followed by ligand recombination, in ferrous cyt c is studied using ultrafast laser spectroscopy.

Published
2000

7. Investigations of photolysis and rebinding kinetics in myoglobin using proximal ligand replacements

Author

Wenxiang Cao, Xiong Ye, Sjodin, Theodore, Christian, James F., Demidov, Andrey A., Berezhna, Svirlana, Wei Wang, Barrick, Doug, Sage, J. Timothy, and Champion, Paul M.

Subjects
Raman spectroscopy -- Analysis, Photolysis -- Analysis, Myoglobin -- Spectra, Biological sciences, Chemistry
Abstract

The laser photolysis and time-resolved Raman spectroscopy of CO-bound H93G myoglobin (Mb) mutants are used to investigate the influence of the proximal ligand on the CO rebinding kinetics. The measurements indicate that perturbations associated with the proximal heme ligand can dramatically influence the diatomic ligand rebinding kinetics.

Published
2004

11. Nonlinear optical studies of ultrafast carrier dynamics in silicon and a molecular thin film on a silver surface

Author

Sjodin, Theodore A and Sjodin, Theodore A

Abstract

Transient grating (TG) scattering and second harmonic generation (SHG) were used to study dynamical and structural properties of semiconductors and molecular thin films on metal surfaces. In the first part of this dissertation, the dynamics of photoexcited carriers generated near a silicon surface were studied on femtosecond timescales using transient grating scattering in a reflection configuration. Experiments were conducted to study both carrier concentration and orientation gratings. In the concentration grating study, the lifetime for hot carrier relaxation for electrons excited 1.4 ± 0.6 eV above the conduction bandedge and their corresponding holes was determined to be 240 fs at carrier densities below 1020 cm–3 . At carrier densities higher than 5 × 1020 cm –3, the relaxation lifetime increased sharply providing the first direct evidence for charge screening of carrier-phonon scattering in silicon. In the orientation grating study, a transient grating signal was observed whose origin is believed to be from anisotropic state-filling. The time profile of the transient grating signal mimics the observed time profile for the input pulses measured from correlation experiments. This indicates that the momentum reorientation time in silicon is much faster than the input pulsewidth of 100 fs. TG studies were also conducted to measure the ambipolar diffusivity and carrier recombination rate at very high carrier densities (> 1020 cm–3). In the second part of this dissertation, second harmonic generation was used to study thin pyridine films on a silver surface (Ag(111)). For films grown at 100 K, an irreversible phase transition from a disordered solid to an ordered solid was observed when the films were annealed above 125 K. An analytical model of the second harmonic generation from the annealed pyridine films is presented. It was determined that the annealed films were composed of randomly oriented crystallites with an average length distribution greater than 700 nm

Published
1998

14. Investigations of Anharmonic Low-Frequency Oscillations in Heme Proteins

Author

Rosca, Florin, primary, Kumar, Anand T. N., additional, Ionascu, Dan, additional, Ye, Xiong, additional, Demidov, Andrey A., additional, Sjodin, Theodore, additional, Wharton, David, additional, Barrick, Douglas, additional, Sligar, Stephen G., additional, Yonetani, Takashi, additional, and Champion, Paul M., additional

Published
2001
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17. Investigations of coherent vibrational oscillations in myoglobin

Author

Rossca, Florin, Kumar, Anand T.N., Ye, Xiong, Sjodin, Theodore, Demidov, Andrey A., and Champion, Paul M.

Subjects
Chemistry, Physical and theoretical -- Research, Chemicals, plastics and rubber industries
Abstract

Results of applying femtosecond coherence spectroscopy to the heme protein myoglobin are presented. Investigations included photostable samples of deoxy myoglobin and photochemically active samples of the nitric oxide adduct.

Published
2000

29. Complex Formation of Cytochrome P450camwith Putidaredoxin

Author

Unno, Masashi, Christian, James F., Sjodin, Theodore, Benson, David E., Macdonald, Iain D.G., Sligar, Stephen G., and Champion, Paul M.

Abstract

We have performed resonance Raman studies on ferrous NO- and CO-adducts of cytochrome P450camand investigated the effects of diprotein complex formation with reduced putidaredoxin. We have found that the Fe-NO stretching mode of NO-P450camcan be resolved into two peaks at 551 and 561 cm−1, and the binding of putidaredoxin increases the intensity of the high frequency component. Because the Fe-NO mode has been shown to be more sensitive to the nature of the heme proximal ligand than to the distal pocket environment, such a perturbation upon putidaredoxin binding is suggestive of changes in conformation or electronic structure that affect the proximal iron-cysteine bond. In accordance with this idea, the isotope shifts for the Fe-XO stretching and Fe-X–O bending modes (X = N or C) are insensitive to the presence or absence of putidaredoxin, indicating that the geometry of the Fe-X–O unit is not significantly altered by the complex formation. On the other hand, complex formation does induce a perturbation of the low frequency heme vibrational modes, suggesting that alterations of the heme electronic structure and/or geometry take place when putidaredoxin binds. We also find that cytochromeb5minimally affects the heme active site of the enzyme, although both putidaredoxin and cytochromeb5bind to the same or similar site on P450cam. These observations suggest that there is a key specific interaction between P450camand putidaredoxin, and that this interaction increases the population of a protein conformation that exhibits structural and/or electronic distortions of the heme group associated with the proximal side of the heme pocket and the S → Fe electron donation. These electronic and structural changes are potentially correlated with H-bonding to the proximal cysteine.

Published
2002
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