A detailed spectroscopic study was carried out on 3-hydroxyflavone in order to elucidate the mechanism which is responsible for the anomalous fluorescence of flavonols in the green-yellow region. A combination of absorption and luminescence measurements indicated that the green emission in 3-hydroxyflavone is due to excited state tautomerization of the molecule by an intramolecular proton transfer mechanism. Excitation spectra, deuteration studies, and comparison with the luminescence behavior of the corresponding methylated analogue confirmed the proton transfer mechanism. In a rigid hydrocarbon or ether glass at 77 K, the green emission is replaced by a predominant UV-violet fluorescence of the normal molecule, in the usual vibrational envelope inversion relationship with the absorption spectrum. The extraordinary viscosity dependence of the tautomerization process has been explained in terms of the mechanical viscous-flow-barrier model of Dellinger and Kasha. Luminescence measurements were performed at various temperatures between 25 K and ambient temperature. The gradual changes in the ratio of normal vs. tautomer emission appeared to follow the expectations according to the above model. / The studies on 3-hydroxyflavone were extended to other flavonols, having additional hydroxy substituents. The general findings were similar to 3-hydroxyflavone, with characteristic minor differences. The molecules 5-hydroxyflavone and 7-hydroxyflavone were also investigated, in order to compare their luminescence behavior with that of 3-hydroxyflavone. The three molecules were found to exhibit very distinct and contrasting luminescence properties. Both ground and excited state ionization were indicated in 7-hydroxyflavone, while in 5-hydroxyflavone a non-adiabatic proton tranfer mechanism, leading to rapid radiationless deactivation of the excited state, seems very probable. / A study was undertaken on the pigment contents of near-white cultivars of Hemerocallis in order to provide guidelines on hybridization programs directed toward production of blue cultivars. The cultivars were divided into four classes, chiefly on the basis of absorption profiles of their methanolic extracts. Flavonols were found in one class only, while carotenoids and hydroxycinnamic acids were present in all classes. / Finally, an attempt was made to characterize synthetic anthocyanin- copigment complexes on the basis of absorption and luminescence measurements. / Source: Dissertation Abstracts International, Volume: 41-12, Section: B, page: 4363. / Thesis (Ph.D.)--The Florida State University, 1980.

Source: Dissertation Abstracts International, Volume: 41-09, Section: B, page: 3289. / Thesis (Ph.D.)--The Florida State University, 1980.

This series of experiments systematically evaluates the effect of phospholipid headgroup structures on the interaction between rhodopsin and phospholipids. Three types of experiments are reported. / First, the effect of rhodopsin incorporation on the DMPC and DMPS gel-to-liquid-crystalline phase transition is analyzed with ESR techniques. Partial, binary phase diagrams of the DMPS- and DMPC-rhodopsin systems at pH = 7.0 are constructed by studying the partitioning of Tempo between polar and hydrophobic domains as a function of temperature and system composition. A main result of this analysis is that rhodopsin broadens and reduces the amplitude of the DMPS phase transition to a much smaller extent than the DMPC phase transition. When interpreted in terms of theoretical treatments of integral protein-lipid interactions, this indicates that rhodopsin has a lower affinity for DMPS than DMPC. / Second, ESR experiments involving nitroxide-labeled phosphatidylcholine, phosphatidylserine and phosphatidic acid are reported. / Third, the effect of the major headgroup classes of phospholipids on the conformational stability of rhodopsin is investigated. / This series of experiments demonstrate that the structure of the fatty acid chains is as important as the headgroup structure in determining the stabilization ability of a phospholipid. / Source: Dissertation Abstracts International, Volume: 42-09, Section: B, page: 3550. / Thesis (Ph.D.)--The Florida State University, 1981.

The cytocidal and radiosensitizing effects of two newly developed 2-nitroimidazole derivatives (Ro 03-8799 and RSU-1164) were evaluated with the original compound, misonidazole, serving as a reference agent. More specifically, euoxic and hypoxic BP-8 murine sarcoma cells were exposed for up to 3 hours to various concentrations of the three nitroimidazole derivatives, with or without irradiation, and the resulting cell lethality was monitored with the $\sp{125}$IUdR prelabeling assay. When cell death was evaluated as a function of drug molarity, the three nitroimidazoles displayed widely different toxicities, but when expressed in terms of toxicity ratio between euoxic and hypoxic cells, all three drugs showed nearly identical toxicity differentials of 16 to 18 in 1 hour drug incubation experiments. Prolonging the treatment period to 3 hours with RSU-1164, the toxicity ratio was increased significantly from 16 to 73. This increase was attributed to the bifunctional action of RSU-1164 as a combined electron-affinic and alkylating agent, with the alkylation component of hypoxic cell killing becoming more pronounced after prolonged drug incubation. Combined administration of hyperthermia and nitroimidazoles increased drug-induced cell lethality for all three agents, but did not materially change the relative toxicity differential between euoxic and hypoxic cells. / The radiosensitizing effects of the three compounds were studied at sublethal drug doses, with the drug concentrations adjusted to provide equitoxic (isosurvival)treatment conditions. Under thse experimental conditions, all three drugs displayed equal radiosensitizing effects in short term drug exposures which measure mainly the so-called "oxygen-mimetic" component of radiosensitization. However, with longer drug incubation periods a second component of sensitization known as "preincubation effect" or "damage interaction" became apparent. The magnitude of this damage interaction effect at equitoxic doses for RSU-1164 produced significantly higher damage interaction than the other two agents. / In conclusion, based on cellular toxicity and radiosensitization data, Ro 03-8799 appears to offer no advantage over misonidazole as a selective cytocidal and radiosensitizing agent for hypoxic cells, but RSU-1164 does provide a moderate therapeutic advantage. Additional factors operating in intact animals could further enhance the potential of RSU-1164 and could also serve to make Ro 03-8799 more effective than misonidazole as an adjuvant to chemotherapy and radiotherapy of cancers. (Abstract shortened with permission of author.) / Source: Dissertation Abstracts International, Volume: 49-10, Section: B, page: 4126. / Major Professor: Kurt G. Holer. / Thesis (Ph.D.)--The Florida State University, 1988.

The structural motif and backbone dynamics of the gramicidin-A transmembrane channel in a membrane environment have been investigated using solid-state $\sp{15}$N NMR. Recent determinations of the $\sp{15}$N chemical shift anisotropy tensor with respect to the molecular frame enable the quantitative evaluation of the $\sp{15}$N chemical shift resonances obtained from oriented dimyristoylphosphatidylcholine (DMPC) bilayer samples containing specific-site $\sp{15}$N-labeled gramicidin. / Spectra obtained from oriented samples in the liquid-crystalline phase have been used to verify the $\beta$-type hydrogen-bonding pattern of the helical backbone, and to determine that in these DMPC bilayer preparations the gramicidin channel is right-handed. In addition, these data place constraints on the C$\sb\alpha$-C$\sb\alpha$ axis orientation of individual peptide planes relative to the helix axis. / Spectra obtained from oriented samples in the gel phase have been analyzed to yield a spatial model for local motion. This model includes the axis of motion, the mean orientation, and the maximum amplitude of displacement for individual peptide planes. Specific sites in the first turn of the amino terminus were investigated, with emphasis on the Ala$\sb3$ and Leu$\sb4$ linkages for which the orientation of the $\sp{15}$N tensor with respect to the molecular frame has been determined. The effects of two well defined smectic layer defect structures, parabolic focal conics (PFC's) and oily streaks, are included in the spectral simulations. It is concluded that in the absence of ions, large amplitude motions are not present in the peptide planes of the first turn of the helix. A detailed characterization of bilayer surface geometry is presently the limiting factor in the use of this technique for probing the spatial extent of local motions in integral membrane proteins. / Source: Dissertation Abstracts International, Volume: 51-04, Section: B, page: 1604. / Major Professor: Timothy Albert Cross. / Thesis (Ph.D.)--The Florida State University, 1990.

Histone genes differ from other eucaryotic genes in that they lack introns and are not polyadenylated. The levels of histone mRNAs are coordinately regulated with DNA synthesis. mRNA stability is a major determinant of histone mRNA levels and histone mRNAs are rapidly degraded when DNA synthesis is inhibited. This thesis examines sequence requirements for both processing and degradation of histone mRNA. The highly conserved terminal stem-loop of the histone mRNA is necessary and sufficient to mediate regulated degradation and is also necessary for processing the 3$\sp\prime$ end of the histone mRNA. Histone mRNAs are degraded during translation and the stem-loop must be less than 300 nucleotides downstream of the termination codon for proper regulation of degradation. No particular sequence in the 4-base loop of the stem-loop is necessary for proper degradation since RNAs with changes in the sequence of these bases are regulated normally. A disruption of the base pair at the top of the stem however abolishes regulation of degradation and the mRNA is stable when DNA synthesis is inhibited. Changes in the sequence of the bases of the loop also caused the mRNA to be processed inefficiently. Taken together, these data suggest that degradation occurs on the ribosome and that the stem-loop structure is specifically recognized. A wild type loop sequence is not sufficient for efficient processing since a gene with the terminal stem-loop at the end of histone mRNA has multiple functions in histone mRNA metabolism. A link between the lack of introns in histone genes and lack of polyadenylation of histone mRNAs has been demonstrated. Thus introduction of intron(s) into the histone H2a gene interferes with 3$\sp\prime$ end formation resulting in substantial reduction in the amount of histone mRNA with a terminal stem-loop and a parallel increase in the amount of / polyadenylated histone mRNA. It is proposed that this occurs because a nascent spliceosome directs 3$\sp\prime$ end formation. / Source: Dissertation Abstracts International, Volume: 51-04, Section: B, page: 1605. / Major Professor: William F. Marzluff. / Thesis (Ph.D.)--The Florida State University, 1990.

Liquid-crystalline phase formation is concentrated DNA solutions with the ionic strengths of 0.01, 0.3 and 1 M Na$\sp{+}$ was investigated using phosphorus-31 NMR spectroscopy and optical microscopy. The phase diagrams for isotropic to liquid-crystalline transitions were determined for all three ionic strengths from $\sp{31}$P NMR data and were found to be in good agreement with theoretical predictions of P. J. Flory (Proc. Roy. Soc. A 234, 73; 1956) and Stroobants et al. (Macromolecules 19, 2232; 1986). The critical DNA concentration required for the anisotropic phase formation was found to be weakly dependent on ionic strength, indicating that the effective DNA radius is not strongly dependent on ionic strength. / Two types of mesophases were formed in solutions of all ionic strengths investigated: a weakly birefringent, precholesteric phase and a cholesteric phase. In addition, concentrated solutions with DNA concentrations exceeding 250 mg/mL in 0.01 M and 0.3 M Na$\sp{+}$ buffer exhibited microscopic textures similar to the textures observed in smectic phases formed in solutions of small molecules, indicating a possible two-dimensional ordering of DNA helices. / The sodium-DNA interactions in solutions with DNA concentrations in the range of 10-300 mg/mL and ionic strengths of 0.01 and 1 M Na$\sp{+}$ were investigated using sodium-23 NMR. The longitudinal relaxation rate of bound ions in the range of DNA concentrations of 10-200 mg/mL was found to be $\sim$200 Hz in 0.01 M Na$\sp{+}$ buffer and $\sim$380 Hz in 1 M Na$\sp{+}$ buffer. The relaxation rate was larger in samples which exhibited cholesteric ordering of DNA molecules. / Quadrupole splitting was observed in samples in which the cholesteric phase first appeared: at 190 mg/mL in 0.01 M Na$\sp{+}$ and 250 mg/mL in 1 M Na$\sp{+}$ buffer. The magnitude of quadrupole splitting decreased with increasing DNA concentration in 0.01 M Na$\sp{+}$ buffer and remained relatively constant in 1 M Na$\sp{+}$ buffer. In addition, the quadrupole splitting changed sign when the temperature was increased from 20 to 60 $\sp\circ$C. / Source: Dissertation Abstracts International, Volume: 49-08, Section: B, page: 2979. / Major Professor: Randolph Lynn Rill. / Thesis (Ph.D.)--The Florida State University, 1988.

The purpose of this investigation was to determine if there can be transport of vibrational energy along alpha helices by means of a soliton mechanism. This has been proposed by A. S. Davydov, and, if proven correct, would be highly significant for the interpretation of structure and function in biological macromolecules. / The approach necessary to generate dynamical solutions with soliton character for the helix, is one of forming a reduced Hamiltonian for the amide I vibrational modes, i.e. replacing 'background' modes, to which they are coupled, with quantum mechanical averages. As a result the total wavefunction has a semiclassical form, i.e. a product of background and 'primary' (amide I) wavefunctions. / Since such product forms for the wavefunctions of interacting systems are not generally valid we sought a way to describe the composite system exactly. This we achieved by means of two simple transformations of the total Hamiltonian, which allowed the extraction of dynamically significant terms. The simulations were performed on a Cyber 205, by means of a highly vectorized algorithm for the transformed Hamiltonian. / The results of these studies were that no soliton-like behavior was observed. Energy, initially localized, spreads down the helix more slowly, but the width of the excitation packet is wider than if there was no background coupling. / Source: Dissertation Abstracts International, Volume: 49-08, Section: B, page: 2979. / Major Professor: William C. Rhodes. / Thesis (Ph.D.)--The Florida State University, 1988.

Source: Dissertation Abstracts International, Volume: 40-06, Section: B, page: 2495. / Thesis (Ph.D.)--The Florida State University, 1979.

Source: Dissertation Abstracts International, Volume: 40-06, Section: B, page: 2495. / Thesis (Ph.D.)--The Florida State University, 1979.