No description available.

Rubisco activase operates as the chaperone responsible for maintaining the catalytic competency of Ribulose 1,5-bisphophate carboxylase oxygenase (Rubisco) in plants. Rubisco is notoriously inefficient, rapidly self-inactivating under physiological conditions. Rubisco activase uses the power released from the hydrolysis of ATP to power a conformational change in Rubisco, reactivating it. Rubisco activase has been previously shown to form a large range of species in solution; however, little has been done to relate the size of oligomeric species and physiological activity. In this thesis data is presented from a range of biophysical techniques including analytical ultracentrifugation, static light scattering, and small angle X-ray scattering combined with activity assays to show a strong relationship between oligomeric state and activity. The results suggest that small oligomers comprising 2-4 subunits are sufficient to attain full specific activity, a highly unusual property for enzymes from the AAA+ family. Studies utilising a number of Rubisco activase variants enabled the determination of how Rubisco and Rubisco activase may interact within a plant cell. A detailed characterisation of the α-, β-, and a mixture of isoforms further broadened our knowledge on the oligomerisation of Rubisco activase. Of particular importance was the discovery of a thermally stable hexameric Rubisco activase variant. It is hoped that these findings may contribute to development of more heat tolerant Rubisco activase and lead research into more drought resilient crop plants.

Centrifugation of coconut milk resulted in cream, skim milk, and insoluble solids. Proteins were isolated from skim milk by the addition of acid, with or without heating. The separation and isolation gave the following coconut protein preparations: coconut milk, coconut skim milk, insoluble solids, acid precipitate, and acid-heat precipitate. / Trypsin inhibitory activity (TIA) of the coconut protein preparations was relatively low while tryptic digestibility of the isolated proteins was considerably lower than those of the coconut milk and skim milk, the digestibility of coconut protein preparations was lower than that of casein. In general, the emulsifying and farming properties of coconut protein preparations were lower than casein. The insoluble solids showed the highest viscosity when compared with the coconut protein preparations. In contrast to the whey protein concentrate (WPC), the apparent strain of gels from the acid precipitate increased as the pH increased. The gelation properties at pH 3 of the insoluble solids were better than WPC. / The estimated molecular weight by size-exclusion chromatography of coconut protein preparations gave 3 fractions with MW ranging from 6850 Da to 229402 Da. In native PAGE, coconut proteins were separated into at least 3 subunits and under SDS-denatured conditions, the major protein subunits showed MW of 54531 Da and 25008 Da, respectively. RP-HPLC separation of coconut milk, acid precipitate, and acid-heat precipitate gave 3 fractions containing several species of MW ranging between 35574 Da to 51209 Da when analyzed by mass spectometry.

Potato is a major part of the human diet in many countries of the world, providing substantial levels of carbohydrate, protein, and vitamins. This study examined the tuber protein content. In the first part of the research, total soluble protein (TSP) and patatin concentration were determined in periderm, cortex, and pith, in tubers of 20 important potato cultivars. TSP concentration was greater in periderm and lesser in cortex and pith tissues. Patatin was present in all tuber tissues but with the opposite pattern, less in periderm and greater in cortex and pith tissues. For intercultivar comparisons, a means of converting the specific tissue-based TSP and patatin data (dry weight) into a uniform weight whole tuber basis was developed. This relied on conversion factor values that were generated from percent weight tissue proportion and percent dry matter for each tissue layer. Cultivars with relatively more or less TSP and patatin in each tissue layer, and on a whole tuber basis, were identified. In the second part of the study, disassembly of chimeral (Russet Burbank) and putatively chimeral (Alpha, Bintje, Red Gold) tubers into their component genotypes was evaluated as a strategy for the production of intraclones with altered protein content. Explants were selected from tissue with greater or lesser protein levels and somatic embryogenesis was used to produce regenerants from each tissue source. Russeting was used as a phenotypic marker and TSP as a biochemical marker. Russet Burbank was confirmed as a periclinal chimera, although chimeral instability was evident, since some non-chimeral regenerants showed displacement of LI tunic cells with the russeting mutation into the pith. Red Gold was "uncovered" as an LII periclinal chimera (Red-Gold-Red). The value of chimeral disassembly in explaining an important component of somatic variation was clearly seen with this cultivar. The inconsistent TSP distribution in Russet Burbank intraclones proved that TSP was not distributed in a periclinal chimeral manner, as initially hypothesized. However, there was clear variation in protein content in the tubers of non-chimeral regenerants. Periclinal chimeral disassembly and somatic embryogenesis are potentially useful technologies for the production of improved intraclones of potato.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 147-160). Also available on the World Wide Web.

Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains ix, 125 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 98-125).

Thesis (M.S.)--Brigham Young University. Dept. of Microbiology & Molecular Biology, 2004. / Includes bibliographical references (p. 58-61).

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Shridhar K. Sathe, Florida State University, College of Human Sciences, Dept. of Nutrition, Food, and Exercise Science. Title and description from dissertation home page (viewed Sept. 23, 2004). Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Department of Biochemistry and Molecular Biology, March 2003. / Includes bibliographical references. Also available on the Internet.