Characterization of acid catalytic domains for cellulose hydrolysis and glucose degradation.

Cellulolytic enzymes consist of a catalytic domain, a linking peptide, and a binding domain. The paper describes research on carboxylic acids that have potential as catalytic domains for constructing organic macromolecules for use in cellulose hydrolysis that mimic the action of enzymes. The tested domains consist of the series of mono-, di-, and tricarboxylic acids with a range of pK(a)'s. This paper systematically characterizes the acids with respect to hydrolysis of cellobiose, cellulose in biomass, and degradation of glucose and compares these kinetics data to dilute sulfuric acid. Results show that acid catalyzed hydrolysis is proportional to H+ concentration. The tested carboxylic acids did not catalyze the degradation of glucose while sulfuric acid catalyzed the degradation of glucose above that of water alone. Consequently, overall yields of glucose obtained from cellobiose and cellulose are higher for the best carboxylic acid tested, maleic acid, when compared to sulfuric acid at equivalent solution pH.

Optimal packing characteristics of rolled, continuous stationary-phase columns.

Rolled, continuous stationary phases were constructed by tightly rolling and inserting a whole textile fabric into a chromatography column. This work reports the column performance, in terms of plate height, void fraction, and resolution, of 10 cellulose-based fabrics. The relation between fabric structural properties of yarn diameter, fabric count, fabric compressibility, and column performance are quantitated. General requirements, including reproducibility of packing, for choosing fabrics to make a good SEC column are identified. This research showed that the packed columns have an optimal mass of fabric that minimizes plate height and maximizes resolution, in a manner that is consistent with chromatography theory. Mass of material packed is then an important column parameter to consider when optimizing columns for the rapid desalting of proteins. Proteins were completely separated from salt and glucose in less than 8 min at a pressure drop less than 500 psi on the rolled, continuous stationary-phase columns. These results, together with stability and reproducibility, suggest potential industrial applications for cellulose-based rolled, continuous stationary-phase columns where speed is a key parameter in the production process.

Modeling pore size distribution in cellulose rolled stationary phases.

Rolled stationary phases are fabrics (i.e., nonparticulate phases) that rapidly separate proteins from salts on the basis of size exclusion. Pore size and pore size distributions in the stationary phase determine how different size molecules distribute between the stationary and mobile phases in liquid chromatography columns. The potential for size exclusion chromatography by fabrics is not initially obvious because their interlaced structures are atypical for size exclusion supports. A simple logistic model fits the pore size distribution of a rolled stationary phase when pore sizes were measured using PEG, Dextran, D2O, glucose, and NaCl probes. When the fabric is treated with cellulase enzymes, the water-accessible pores uniformly decrease and peak retention is lower. The logistic function model captures this result and enables comparison of pore size distribution curves between enzyme-treated and untreated fabrics in rolled stationary phase columns.