Structure analysis of carboxymethyl starch by capillary electrophoresis and enzymic degradation

Carboxymethyl starches (CMS) with a degree of substitution (DS) in the range of 1.2 to 1.5 were analysed by capillary electrophoresis (CE) after hydrolysis and reductive amination in a borate buffer. The monomer composition determined was compared to data calculated by the statistical models of Spurlin and Reuben. In addition, the starch derivatives were exhaustively degraded by alpha-amylase and amyloglucosiclase and the amount of glucose liberated was determined. Results were discussed with regard to derivatisation conditions and properties of the carboxymethyl starches

Hydrolysis of maltoheptaose in flow through silicon wafer microreactors containing immobilised alpha-amylase and glycoamylase

In this study,a silicon micro immobilised enzyme reactor (mu IMER) has been applied for hydrolysis of maltoheptaose as a model maltodextrin and starch using immobilised otamylase (from Aspergillus oryzae) and glycoamylase (from Aspergillus niger). The influence of several parameters was investigated such as immobilisation chemistry, buffer constituents, pH, temperature, flow rate and substrate concentration. The conversion efficiency profile of the substrate was measured and the long-term stability of the reactor was tested. For separation and detection of the formed hydrolysis products, high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was used. The results show that the mu IMERs can also be used for hydrolysis of starch and also additionally be connected directly on-line with, e.g., liquid chromatography, making it possible to perform on-line characterisation and analysis of starch hydrolysis products

New structural features of the antigenic extracellular polysaccharides of Penicillium and Aspergillus species revealed with exo-beta-D-galactofuranosidase.

To study the structures of the epitopes of the extracellular polysaccharides from Penicillium and Aspergillus species, an exo-beta-D-galactofuranosidase was purified from a commercial crude enzyme preparation from Trichoderma harzianum. Analysis of ring size and linkage position of the galactose residues of the extracellular polysaccharide of Penicillium digitatum, before and after enzymatic treatment, was determined by the reductive-cleavage technique. In addition to terminal and beta (1-5)-linked galactofuranosides, beta (1-6)-linked and beta (1,5,6)-linked branched galactofuranose residues could be identified. After degradation with the purified exo-beta-D-galactofuranosidase, all initial linkages of the galactofuranose residues were still present, but the amount of beta (1-5)-linked galactofuranose residues had decreased considerably. Treatment of the extracellular polysaccharides of Penicillium and Aspergillus species with the purified exo-beta-D-galactofuranosidase resulted in complete disappearance of the enzyme-linked immunosorbent assay reactivity of these polysaccharides, using immunoglobulin G antibodies raised against P. digitatum. Therefore, with the use of this enzyme, it was proved that the beta (1-5)-linked galactofuranosyl residues only are responsible for the antigenicity of the extracellular polysaccharides of Penicillium and Aspergillus molds. A new structural model for the antigenic galactofuranose side chains of the galactomannan from P. digitatum is proposed