No description available.

Thesis (Ph.D.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 109-119.

Flavocytochrome b2 catalyzes the oxidation of lactate to pyruvate. Primary deuterium and solvent kinetic isotope effects have been used to determine the relative timing of cleavage of the lactate OH and CH bonds by the wild type enzyme, a mutant protein lacking the heme domain, and the D282N enzyme. The DVmax and D(V/Klactate) values are both 3.0, 3.6 and 4.5 for the wild type enzyme, flavin domain and D282N enzymes, respectively. The D20Vmax values are 1.38, 1.18, and 0.98 for the wild type enzyme, the flavin domain, and the D282N enzyme; the respective D20(V/Klactate) values are 0.9, 0.44, and 1.0. The Dkred value is 5.4 for the wild type enzyme and 3.5 for the flavin domain, whereas the D2Okred is 1.0 for both enzymes. The V/Klactate value for the flavin domain increases 2-fold at moderate concentrations of glycerol. The data are consistent with the lactate hydroxyl proton not being in flight in the transition state for CH bond cleavage and there being an internal equilibrium prior to CH bond cleavage which is sensitive to solution conditions. Removal of the hydroxyl proton may occur in this pre-equilibrium. Tryptophan 2-monooxygenase catalyzes the oxidative decarboxylation of tryptophan to indoleacetamide, carbon dioxide and water. Sequence alignments identified this enzyme as a member of the L-amino acid oxidase family. The tyrosine and arginine residues in L-amino acid oxidase that bind the carboxylate of o-aminobenzoate are conserved and correspond to Tyr413 and Arg98 in tryptophan 2-monooxygenase. Mutation and characterization of the Y413A, Y413F, R98K and R98A enzymes indicate that these residues are in the active site and interact with the substrate. Deletion of the OH group of Tyr413 increases the Kd for the substrate and makes CH bond cleavage totally rate limiting. The pH V/Ktrp rate profile for the Tyr413 mutant enzymes shows that this residue must be protonated for activity. For both the R98A and R98K enzymes flavin reduction is rate limiting. The Vmax and V/Ktrp pH profiles indicate that the unprotonated form of the substrate is the active form for activity.

Graduation date: 1991

The linking of breeding and nonbreeding grounds of migratory birds is of great conservation and theoretical importance. In theory, connecting these geographically disparate areas allows for a more complete understanding of annual events, and a first step into identifying where in the annual cycle limitations to fitness may be occurring. <p>The Loggerhead Shrike (<i>Lanius ludovicianus</i>) is a Species at Risk in Canada, and its decline is attributed to habitat loss on both the breeding and wintering grounds. In the fall, Loggerhead Shrikes from breeding areas of prairie Canada (<i>L. l. excubitorides</i>), the focus of this study, move south along the Gulf States of the United States and Mexico to wintering areas that are already occupied year-round by resident shrikes. However, the habitat structure and variability for both migrants and resident Loggerhead Shrikes have not been studied well on the wintering grounds. Thus, it has been difficult to adequately evaluate the relative contribution of changes in wintering areas to the decline of Loggerhead Shrike populations. To identify the wintering grounds of Loggerhead Shrikes that breed in prairie Canada, I used stable hydrogen isotope (δD) analysis of feathers and claws and microsatellite DNA from feathers. In North America, δD measurements from feathers provide information on latitude of origin, while DNA can be related to an affiliation to a breeding population. Since several authors suggested that Loggerhead Shrike completed their preformative and formative molt on the breeding grounds prior to fall migrations, I reasoned that δD analysis of tertial feathers sampled on the wintering grounds would correspond to δD in precipitation from the breeding grounds. Similarly, I used DNA microsatellite markers and Bayesian clustering analysis to detect patterns of population genetic structure within the range of Western Loggerhead Shrikes (<i>L. l. excubitorides</i>) in Canada and consequently use these to infer breeding origin of shrikes sampled in Mexico. I based the categorization of resident and migrant Loggerhead Shrikes sampled in Mexico on δD analysis of feathers. Based on evaluation of observed and expected δD values of feathers, I determined that migrant shrikes used northeastern (63.8%) and south-central (73.7%) Mexico to winter. Microsatellite DNA and assignment tests, suggested that wintering migrant shrikes occupied north-central (18.6%) and northeastern (20.3%) Mexico. Differential habitat occupancy analyses, suggested that, in northeastern Mexico, wintering sites occupied by Loggerhead Shrike sites were structurally different from random unoccupied sites (MRPP, T = -8.04, P < 0.001, n = 354). An important difference was that, on average, occupied habitat contained shorter tall shrubs and huisache and fewer tall shrubs, mesquite and huisache. Similarly, residents shrikes occupied structurally different habitats (MRPP, T = -2.95, P = 0.01, n = 146) that had less percent cover of bare ground than those sites occupied by migrants. Based on these habitat results, I surmise that habitat availability may be a limiting factor for both resident and migratory shrike populations in northeastern Mexico.

The linking of breeding and nonbreeding grounds of migratory birds is of great conservation and theoretical importance. In theory, connecting these geographically disparate areas allows for a more complete understanding of annual events, and a first step into identifying where in the annual cycle limitations to fitness may be occurring. <p>The Loggerhead Shrike (<i>Lanius ludovicianus</i>) is a Species at Risk in Canada, and its decline is attributed to habitat loss on both the breeding and wintering grounds. In the fall, Loggerhead Shrikes from breeding areas of prairie Canada (<i>L. l. excubitorides</i>), the focus of this study, move south along the Gulf States of the United States and Mexico to wintering areas that are already occupied year-round by resident shrikes. However, the habitat structure and variability for both migrants and resident Loggerhead Shrikes have not been studied well on the wintering grounds. Thus, it has been difficult to adequately evaluate the relative contribution of changes in wintering areas to the decline of Loggerhead Shrike populations. To identify the wintering grounds of Loggerhead Shrikes that breed in prairie Canada, I used stable hydrogen isotope (δD) analysis of feathers and claws and microsatellite DNA from feathers. In North America, δD measurements from feathers provide information on latitude of origin, while DNA can be related to an affiliation to a breeding population. Since several authors suggested that Loggerhead Shrike completed their preformative and formative molt on the breeding grounds prior to fall migrations, I reasoned that δD analysis of tertial feathers sampled on the wintering grounds would correspond to δD in precipitation from the breeding grounds. Similarly, I used DNA microsatellite markers and Bayesian clustering analysis to detect patterns of population genetic structure within the range of Western Loggerhead Shrikes (<i>L. l. excubitorides</i>) in Canada and consequently use these to infer breeding origin of shrikes sampled in Mexico. I based the categorization of resident and migrant Loggerhead Shrikes sampled in Mexico on δD analysis of feathers. Based on evaluation of observed and expected δD values of feathers, I determined that migrant shrikes used northeastern (63.8%) and south-central (73.7%) Mexico to winter. Microsatellite DNA and assignment tests, suggested that wintering migrant shrikes occupied north-central (18.6%) and northeastern (20.3%) Mexico. Differential habitat occupancy analyses, suggested that, in northeastern Mexico, wintering sites occupied by Loggerhead Shrike sites were structurally different from random unoccupied sites (MRPP, T = -8.04, P < 0.001, n = 354). An important difference was that, on average, occupied habitat contained shorter tall shrubs and huisache and fewer tall shrubs, mesquite and huisache. Similarly, residents shrikes occupied structurally different habitats (MRPP, T = -2.95, P = 0.01, n = 146) that had less percent cover of bare ground than those sites occupied by migrants. Based on these habitat results, I surmise that habitat availability may be a limiting factor for both resident and migratory shrike populations in northeastern Mexico.

Flavocytochrome b2 catalyzes the oxidation of lactate to pyruvate. Primary deuterium and solvent kinetic isotope effects have been used to determine the relative timing of cleavage of the lactate OH and CH bonds by the wild type enzyme, a mutant protein lacking the heme domain, and the D282N enzyme. The DVmax and D(V/Klactate) values are both 3.0, 3.6 and 4.5 for the wild type enzyme, flavin domain and D282N enzymes, respectively. The D20Vmax values are 1.38, 1.18, and 0.98 for the wild type enzyme, the flavin domain, and the D282N enzyme; the respective D20(V/Klactate) values are 0.9, 0.44, and 1.0. The Dkred value is 5.4 for the wild type enzyme and 3.5 for the flavin domain, whereas the D2Okred is 1.0 for both enzymes. The V/Klactate value for the flavin domain increases 2-fold at moderate concentrations of glycerol. The data are consistent with the lactate hydroxyl proton not being in flight in the transition state for CH bond cleavage and there being an internal equilibrium prior to CH bond cleavage which is sensitive to solution conditions. Removal of the hydroxyl proton may occur in this pre-equilibrium. Tryptophan 2-monooxygenase catalyzes the oxidative decarboxylation of tryptophan to indoleacetamide, carbon dioxide and water. Sequence alignments identified this enzyme as a member of the L-amino acid oxidase family. The tyrosine and arginine residues in L-amino acid oxidase that bind the carboxylate of o-aminobenzoate are conserved and correspond to Tyr413 and Arg98 in tryptophan 2-monooxygenase. Mutation and characterization of the Y413A, Y413F, R98K and R98A enzymes indicate that these residues are in the active site and interact with the substrate. Deletion of the OH group of Tyr413 increases the Kd for the substrate and makes CH bond cleavage totally rate limiting. The pH V/Ktrp rate profile for the Tyr413 mutant enzymes shows that this residue must be protonated for activity. For both the R98A and R98K enzymes flavin reduction is rate limiting. The Vmax and V/Ktrp pH profiles indicate that the unprotonated form of the substrate is the active form for activity.

Not available / text

Theoretical and experimental aspects of high resolution spectroscopy are discussed. The theoretical work concentrates on the matrix elements of the rigid rotor and molecular hyperfine terms of the Hamiltonian of a rotating molecule. The experimental work consists of Stark cell and beam maser microwave spectroscopy on C1CN and HDO respectively. The theory of rotational spectroscopy is developed in a uniform manner based on the irreducible tensor method. It is shown how the effect of molecular symmetry may be incorporated into this method. The instrumentation required to observe the hyperfine splittings is discussed. This includes descriptions of the Stark cell and molecular beam maser microwave spectrometers. A new tunable C-band resonant cavity is described. The following molecular constants are reported for both common species of C1CN: rotational constant Bₒ, centrifugal distortion constant D(J), quadrupole coupling constant eqQ(k), and spin-rotation constant C(x). Values in MHz for C1CN are as follows: ³⁵C1CN; Bₒ = 5 907.820 ± 0.010, eqQ(C1) = -83.26 ± 0.06, eqQ(N) = -3.59 ± 0.08, C(C1) = -0.006 ± 0.006, C(N) = 0.013 ± 0.010; ³⁷C1CN; Bₒ = 5 847.246 ± 0.008, eqQ(C1) = -65.61 ± 0.06, eqQ(N) = -3.61 ± 0.08, C(C1) = -0.004 ± 0.006, C(N) = 0.010 ± 0.010. The following molecular constants for HDO are reported: quadrupole coupling tensor elements eqQ(D)(gg) and spin-rotation tensor elements C(x)(gg). The values in KHz are as follows: eqQ(D)(aa) = 276.45 ± .88, eqQ(D)(bb) = -110.97 ± 1.46, eqQ(D)(cc) = -165.77 ± 1.10, C(D)(aa) = 1.33 ± .20, C(D)(bb) = -4.38 ± .36, C(D)(cc) = -2.99 ± .24, C(H)(aa) = -58.42 ± .47, C(H)(bb) = -5.46 ± .83, C(H)(cc) = -23.28 ± .10. The values for the constants for C1CN agree with previous values but are more precise. Those for HDO do not agree with previous values but are thought to be more accurate since they are obtained for a larger data base.

No description available.