No description available.

No description available.

No description available.

No description available.

The primary purpose of this study was to (1) develop methods for the analysis of and (2) provide information on the chemical nature of reducing ends in typical cellulose substrates used for the study of cellulolytic enzymes. The studies were designed such that values obtained for cellulose substrates were compared with those obtained for a series of soluble cellooligosaccharides. The initial phase of the study tested the validity of using established colorimetric reducing sugar assays, developed for the measurement of reducing sugars in solution, for the quantification of reducing ends on insoluble substrates. The results demonstrate that published methods give widely differing values for the number of reducing ends per unit weight cellulose. The Cu⁺⁺-based assay, using bicinchoninic acid (BCA) as a color yielding chelator of Cu⁺, is shown to provide values that appear most consistent the properties of the substrates. A method was developed using the Cu⁺⁺-BCA reagent, following a mild sodium borohydride treatment, to provide an estimate of the number of solvent accessible reducing ends on insoluble substrates. The kinetics of sodium borohydride reduction of reducing ends on crystalline cellulose, amorphous cellulose and soluble cellooligosaccharides were compared in order to ascertain the relative reactivity of these reducing ends. The apparent second order rate constants for the reduction of reducing ends associated with the crystalline celluloses were significantly lower than those for the reduction of reducing ends associated with either the insoluble amorphous celluloses or the soluble cellooligosaccharides. These results indicate the reducing ends associated with crystalline celluloses are not extended out from the surface as though mimicking solution phase reducing ends. The relevance of this, as well as the other results, to the behavior of cellulolytic enzymes is discussed. The final phase of the study was the demonstration of both a reducing sugar-based and a viscositybased assay for the detection of a prototypical polysaccharide depolymerizing glycosyl hydrolase, polygalacturonase. / Graduation date: 2004

Thesis (M.S. in engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 21, 2010). "Department of Biological Systems Engineering." Includes bibliographical references.

Thesis (M.S.)--Pennsylvania State University, 2009. / Mode of access: World Wide Web. Thesis advisor: Richard C. Ready.

No description available.

No description available.

The aim of this work was to develop methods of measuring pore size and the related surface area and pore volume, and then to apply these methods in studying the effects of degradation and lignification on these properties. Colloidal gold particles of prescribed sizes (2-10 nm in diameter) were used as molecular probes to determine pore size in maize and rape walls of different cell types. The particles were visualised by electron microscopy, and this indicated that the pore size in maize parenchyma walls was somewhere between 3 and 5 nm. Gas adsorption analysis provides information on pore size, surface area and pore volume, and was used to study cell walls of maize, alfalfa, wheat, timothy, and rape. This showed that the overall porous structure of the plants selected was very similar. The pore size distributions showed that the vast majority of pores had radii less than 3 nm, although wheat and timothy appeared to have a greater number of larger pores. The physical properties of plants containing type 1 walls were also investigated by this method. This illustrated how gas adsorption could be used to detect the changes in porosity and surface area which arise from the extraction of pectic polysaccharides. The effect of degradation on porosity was investigated using the same five plant types as had been studied previously. It was found that there was no great change in the porous structure as the walls were digested, except for wheat and timothy which both lost the larger pores they possessed before degradation. This resulted in pore size distributions more typical of the other three plant types. The data indicated that degradation occurred by a surface erosion process. Porosity and surface area did not alter greatly between cell walls of varying levels of lignification.