An intrinsically shielded hydrogel for the adsorptive recovery of lysozyme

Abstract

The present paper addresses the selective recovery of lysozyme from egg white using CM-dextran (carboxymethyldextran)-based hydrogels containing Cibacron Blue as an affinity ligand and co-immobilized BSA intended to act as a shielding agent to reduce non-specific adsorption. Initial studies using pure lysozyme were conducted that indicated that the adsorption capacity increased with ligand density and that adsorption was well described by a Langmuir-type isotherm. The inclusion of BSA as a putative shielding agent did not decrease the adsorption capacity for lysozyme in single-adsorbate experiments. To assess the effectiveness of the shielding strategy, subsequent experiments were conducted with both defined lysozyme/ovalbumin mixtures and hen's-egg white. From these studies, the optimal operating conditions for lysozyme recovery have been determined. These include: optimal initial egg-white concentration [a 10% (v/v) solution of native egg white in the chosen buffer], affinity-ligand density (1.86 mM) and ligand-to-shielding-agent ratio (4:1). The purity of lysozyme obtained from egg white was improved from 69% with a non-shielded hydrogel to 94% with an intrinsically shielded hydrogel. Finally, the possibility of using a protein, rather than dextran-backbone-based, hydrogel was investigated. It was found that BSA could take the place of CM-dextran as the gel backbone in a simplified synthesis, producing a gel which also proved effective for lysozyme recovery with a 30% lysozyme in egg-white solution purified to approx. 92% in a single adsorption-desorption cycle.

Chapter 1. A Brief Introduction to Lignin Structure

“…Especially, combinations of quantitative 13 C solution-state NMR and 2D NMR techniques are sufficiently advanced to obtain detailed insights into LCC structures. [128][129][130] The presence of bonds between polysaccharides and hydroxycinnamic acids such as p-coumaric acid, ferulic acid, and sinapic acid in the cell wall has been proposed. 131,132 Based on intensive research into relationships among lignin, cellulose, and hemicellulose in the past several decades, it was found that ferulic acid residues linked with arabinoxylan via ester linkages between carboxylic acid in ferulic acid and primary alcohol at C5 position in arabinose group, 133 and that ferulic acid also linked to lignin monomers through oxidative coupling pathways to form ferulatepolysaccharide-lignin complexes via ether bonds (Figure 1.5E and G).…”