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Articles 1 - 17 of 17

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Protein-Protein Interaction And Electron Transfer: Case Of Cytochrome F And Cytochrome C6 , Tijana Žarković Grove Jan 2004

Protein-Protein Interaction And Electron Transfer: Case Of Cytochrome F And Cytochrome C6 , Tijana Žarković Grove

Retrospective Theses and Dissertations

We used photo-induced reaction as a tool to look to explore dynamics of the protein-protein interaction between cytochrome f and cytochrome c6 from C. reinhardtii. In our studies of electron transfer between 3Zncyt c6 and cyt f(III) we discovered two distinct intracomplex processes corresponding to electron transfer within diprotein complexes termed persistent and transient. The overall reaction remained biphasic and the rate constants for both processes were invariant to the change of ionic strength within the studied interval. The docking of these proteins is due to strong hydrophobic interaction slightly augmented by weak electrostatic attraction. We used covalent cross-linking ...


Photophysics And Light Induced Photobiology Of Antiviral And Antitumor Agents, Hypericin And Hypocrellin , Jaehun Park Jan 2001

Photophysics And Light Induced Photobiology Of Antiviral And Antitumor Agents, Hypericin And Hypocrellin , Jaehun Park

Retrospective Theses and Dissertations

The dissertation mainly focuses on the excited-state photophysics and the light-induced biological activity of hypericin and its analogs.;Femtosecond laser technology has provided the opportunity to investigate the rapid dynamics of these molecules. Fluorescence upconversion measurements, which monitor only emission from the fluorescent singlet state, demonstrate that hexamethoxy hypericin, which possesses no labile protons, has an instantaneous rise time for its transient response. On the other hand, hypericin shows a clear 10-ps rise time. This confirms excited-state H-atom transfer as the primary photophysical process in hypericin.;Femtosecond transient absorption spectroscopy technique is used to determine if excited state H-atom transfer ...


Interactions And Electron-Transfer Reactions Between Metalloproteins , Milan Miroslav Crnogorac Jan 2000

Interactions And Electron-Transfer Reactions Between Metalloproteins , Milan Miroslav Crnogorac

Retrospective Theses and Dissertations

Electron-transfer reactions are essential for life. Because metalloproteins are involved in electron transport in the cell, it is important to understand the factors that affect recognition, interaction, and reactions of these electron carriers. Cytochrome c is well-characterized electron-carrier protein. The heme protein cytochrome c and the blue-copper protein plastocyanin are well suited for kinetic and mechanistic studies since their structures are known in detail;We investigated the effects of site-directed mutations and viscosity on rate-limiting rearrangement within the complex of cytochrome c and plastocyanin and identified the reactive configuration of the complex. In the reactive configuration of the complex cytochrome ...


Primary Photoprocesses Of Light-Activated Antiviral And Antitumor Agents, Hypericin And Hypocrellin , Alexandre V. Smirnov Jan 1999

Primary Photoprocesses Of Light-Activated Antiviral And Antitumor Agents, Hypericin And Hypocrellin , Alexandre V. Smirnov

Retrospective Theses and Dissertations

The dissertation focuses on the ultrafast primary photoprocesses of the title anti-viral and anti-cancer agents, whose activity depends on light which is also accompanied by photoacidification in vesicles and living cells;By complementing the techniques of time-resolved absorption spectroscopy with those of fluorescence upconversion and applying them to hypericin, hypocrellin A and B, and their methylated analogs that are unable to execute proton transfer, it was demonstrated that intramolecular excited-state hydrogen atom transfer is a dominant primary nonradiative process;For hypocrellin A in viscous solvents such as octanol and ethylene glycol, an absorption transient of ∼10-ps duration, similar to the ...


Application Of Spectral Hole Burning To The Study Of In Vitro Cellular Systems , Nebojsa Milanovich Jan 1999

Application Of Spectral Hole Burning To The Study Of In Vitro Cellular Systems , Nebojsa Milanovich

Retrospective Theses and Dissertations

The high resolution spectroscopic technique of nonphotochemical hole burning (NPHB) was applied to the study of in vitro cellular systems. Suspensions of two well-characterized cell lines were used for these studies: (1) MCF-10F cells, a normal human breast epithelial cell line, and (2) MCF-7 cells, a human breast adenocarcinoma cell line. Both cell lines were stained with the dye aluminum phthalocyanine tetrasulfonate (APT) and prepared for spectroscopic study at liquid helium temperatures. Routinely measured hole burning parameters were obtained for the two cell types and compared in order to differentiate between physical properties of normal and cancer cells;A comparison ...


Theoretical Simulations And Ultrafast Pump-Probe Spectroscopy Experiments In Pigment-Protein Photosynthetic Complexes , Daniel Richard Buck Jan 1998

Theoretical Simulations And Ultrafast Pump-Probe Spectroscopy Experiments In Pigment-Protein Photosynthetic Complexes , Daniel Richard Buck

Retrospective Theses and Dissertations

Theoretical simulations and ultrafast pump-probe laser spectroscopy experiments were used to study photosynthetic pigment-protein complexes and antennae found in green sulfur bacteria such as Prosthecochloris aestuarii, Chloroflexus aurantiacus, and Chlorobium tepidum. The work focused on understanding structure-function relationships in energy transfer processes in these complexes through experiments and trying to model that data as we tested our theoretical assumptions with calculations;Theoretical exciton calculations on tubular pigment aggregates yield electronic absorption spectra that are superimpositions of linear J-aggregate spectra. The electronic spectroscopy of BChl c/d/e antennae in light harvesting chlorosomes from Chloroflexus aurantiacus differs considerably from J-aggregate spectra ...


Hole Burning With Pressure And Electric Field: A Window On The Electronic Structure And Energy Transfer Dynamics Of Bacterial Antenna Complexes , Hsing-Mei Wu Jan 1998

Hole Burning With Pressure And Electric Field: A Window On The Electronic Structure And Energy Transfer Dynamics Of Bacterial Antenna Complexes , Hsing-Mei Wu

Retrospective Theses and Dissertations

Light-harvesting complexes of cyclic symmetry from purple bacteria are studied using absorption and high pressure- and Stark-hole burning spectroscopies. The B800→B850 energy transfer rate of (~2 ps)-1 determined by hole burning and pump-probe spectroscopies is weakly dependent on B800-B850 energy gap varied by pressure and temperature. This resilience is explained in terms of a modified Forster theory with the spectral overlap provided by the B800 fluorescence origin band and weak vibronic absorption of B850. Explanations for the additional sub-picosecond relaxation channel of B800 with excitation on the blue side are given. Pressure and temperature dependent studies show that ...


Characterization Of Biomacromolecules By Nuclear Magnetic Resonance Spectroscopy , Wayne Robert Baker Jan 1996

Characterization Of Biomacromolecules By Nuclear Magnetic Resonance Spectroscopy , Wayne Robert Baker

Retrospective Theses and Dissertations

Two proteins were examined by Nuclear Magnetic Resonance (NMR) spectroscopy. The Emb-1 protein of Daucus carota was found to have few spectral characteristics indicative of a stable tertiary structure. In particular, line-widths were narrow, chemical shift dispersion was poor and nuclear Overhauser effect spectra were sparse. The NMR spectra of Ribonuclease A was examined at a range of pH values and the chemical shifts of a selected number of resonances was plotted as a function of the pH. From these titrations curves pKa values were determined and assigned to specific ionizing groups within the protein based, in part, on physical ...


Photophysics And Activity Of Biological Systems Containing The Optical Probes 7-Azatryptophan And Its Analogs , Rebecca Lynne Rich Jan 1995

Photophysics And Activity Of Biological Systems Containing The Optical Probes 7-Azatryptophan And Its Analogs , Rebecca Lynne Rich

Retrospective Theses and Dissertations

A major use of photophysical apparatus is the study of biological systems, for example, peptides, proteins, and DNA, that contain one or more chromophores. In recent years the incorporation of nonnatural fluorescent compounds into these systems has gained great popularity. A number of optical 'tags' have been suggested as detection tools of structure and function; we propose the use of the tryptophan derivative, 7-azatryptophan, as an intrinsic probe in photophysical analyses of proteins. Not only is this chromophore spectroscopically distinct from tryptophan and all other natural amino acids, but we have demonstrated the successful incorporation of 7-azatryptophan into peptide sequences ...


Line Narrowing Spectroscopic Studies Of Dna-Carcinogen Adducts And Dna-Dye Complexes , Myungkoo Suh Jan 1995

Line Narrowing Spectroscopic Studies Of Dna-Carcinogen Adducts And Dna-Dye Complexes , Myungkoo Suh

Retrospective Theses and Dissertations

Laser-induced fluorescence line narrowing (FLN) and non-line narrowing (NLN) spectroscopic methods were applied to conformational studies of stable DNA adducts of the 7[beta],8[alpha]-dihydoxy-9[alpha],10[alpha]-epoxy-7,8,9, 10-tetrahydrobenzo (a) pyrene (anti-BPDE). Stereochemically distinct (+)-trans-, (-)-trans-, (+)-cis- and (-)-cis adducts of anti-BPDE bound to exocyclic amino group of the central guanine in the oligonucleotide, 5'-d(CCATCGCTACC) · (GGTAGCGATGG), exist in a mixture of conformations in frozen aqueous buffer matrices. The (+)-trans adduct adopts primarily an external conformation with a smaller fraction (~25%) exists in a partially base-stacked conformation. Both cis adducts were found to be ...


Spectral Hole Burning Studies Of Photosystem Ii , Hai-Chou Chang Jan 1995

Spectral Hole Burning Studies Of Photosystem Ii , Hai-Chou Chang

Retrospective Theses and Dissertations

Low temperature absorption and hole burning spectroscopies were applied to the D1-D2-cyt b[subscript]559, and the CP47 and CP43 antenna protein complexes of Photosystem II from higher plants. Low temperature transient and persistent hole-burning data and theoretical calculations on the kinetics and temperature dependence of the P680 hole profile are presented and provide convincing support for the linker model. Implicit in the linker model is that the 684-nm-absorbing Chl a serve to shuttle energy from the proximal antenna complex to reaction center. The stoichiometry of isolated Photosystem II Reaction Center (PSII RC) in several different preparations is also discussed ...


Monolayer Studies Of Novel Synthetic Compounds And Biological Systems , Jingyuan Wang Jan 1994

Monolayer Studies Of Novel Synthetic Compounds And Biological Systems , Jingyuan Wang

Retrospective Theses and Dissertations

A general review on preparation and methods of characterization of monolayers was given in Chapter 1. Different projects were undertaken in the research of this dissertation. Neutron and X-ray reflection studies of fullerene C[subscript]60 and its derivative monolayers were performed in Chapter 1. Neutron and X-ray reflection measurements and surface pressure isotherms of spread films of C[subscript]60-dodecylamine adduct C[subscript]60-(NH[subscript]2(CH[subscript]2)[subscript]11CH[subscript]3][subscript]x and C[subscript]60-propylamine adduct C[subscript]60-(NH[subscript]2C[subscript]3H[subscript]7][subscript]x indicate that these C[subscript]60 ...


Photophysics Of A Novel Optical Probe-7-Azatryptophan And Its Application In The Study Of Protein-Protein Interactions , Yu Chen Jan 1994

Photophysics Of A Novel Optical Probe-7-Azatryptophan And Its Application In The Study Of Protein-Protein Interactions , Yu Chen

Retrospective Theses and Dissertations

Time-resolved and steady-state fluorescence study of the biological optical probe, 7-azatryptophan, its chromophoric moiety 7-azaindole are performed in order to explain the observation that the fluorescence spectrum of 7-azaindole (7-azatryptophan) apparently consists of one band in water ([lambda][subscript]sp\max em = 386nm) whereas in alcohols the spectrum is bimodal (eg. for methanol, [lambda][subscript]sp\max em = 374, 505nm). Careful measurements of the fluorescence decay as a function of emission wavelength indicate a small amplitude of an ~70 ps decaying component at the bluer wavelength and a rising component of the same duration at the redder wavelengths. The small ...


Excited State Structure, Energy And Electron Transfer Dynamics Of Photosynthetic Reaction Centers: A Hole Burning Study , Deming Tang Jan 1990

Excited State Structure, Energy And Electron Transfer Dynamics Of Photosynthetic Reaction Centers: A Hole Burning Study , Deming Tang

Retrospective Theses and Dissertations

The excited state structure, early time energy and electron transfer dynamics for bacterial photosynthetic reaction centers of Rhodoseudomonas viridis, Rhodobacter sphaeroides and green plant photosynthetic reaction center of Photosystem II (PS II) have been determined by hole burning spectroscopy. Transient hole burned spectra of the bacterial reaction centers reveal a special pair Franck-Condon marker mode progression with a superimposed zero phonon hole. Such progression is found to be absent in green plant Photosystem II which raises the question of structural similarities between the PS II and bacterial reaction centers. The excited state decay times are obtained for all systems and ...


Spectral Hole Burning Studies Of Photosystem 1, J. Kevin Gillie Jan 1989

Spectral Hole Burning Studies Of Photosystem 1, J. Kevin Gillie

Retrospective Theses and Dissertations

Persistent spectral hole burning is applied to the reaction center, P700, and the light harvesting chlorophyll protein complexes of Photosystem I. A theory for solid state spectral hole burning is developed that is valid for arbitrarily strong linear electron-phonon coupling within the Condon approximation. Persistent photochemical hole burning of the reaction center P700, reveals that a broad (~300 cm[superscript] -1) hole can be burned into the adsorption profile. The hole profile and its maximum position and intensity dependence on burn wavelength are adequately fit by the electron-phonon coupling theory. The results indicate that the absorption and hole profile are ...


The Effect Of Controlled Ph Upon The Production Of Chemicals In Several Fermentations , Richard James Hickey Jan 1941

The Effect Of Controlled Ph Upon The Production Of Chemicals In Several Fermentations , Richard James Hickey

Retrospective Theses and Dissertations

No abstract provided.


Comparative Studies On The Oxidation Of Polyhydric Alcohols By Biological And Non-Biological Means , Joseph Everett Hunter Jr. Jan 1940

Comparative Studies On The Oxidation Of Polyhydric Alcohols By Biological And Non-Biological Means , Joseph Everett Hunter Jr.

Retrospective Theses and Dissertations

No abstract provided.