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Abstract: A novel class of complex oligosaccharides with a backbone made of twelve β-(1→4)-d-glucosyl units that may be regularly substituted on their primary position with α-d-xylosyl or β-d-(1→2)-galactosyl-α-d-xylosyl residues were readily synthesized using enzymatic hydrolysis of the plant polysaccharide xyloglucan (XG), followed by chemical modifications of the well-defined oligosaccharides and their enzymatic coupling catalyzed by the Cel7B E197A glycosynthase from Humicola insolens. These complex oligosaccharides proved useful for a better understanding of the effects of structural variation of xyloglucan on interactions with bacterial microcrystalline cellulose (BMCC). [Copyright &y& Elsevier]

Synchrotron UV fluorescence microscopy was used for the first time to visualize the adsorption and diffusion of an enzyme while degrading a solid substrate. The degradation pathway of single starch granules by two amylases, optimized for biofuel production and industrial starch hydrolysis, was followed by tryptophan fluorescence (excitation at 280 nm, emission filter at 300-400 nm) and visible light imaging. Thus, both the adsorption of enzyme onto starch granules at 283 nm resolution and the resulting morphological changes were recorded at different stages of hydrolysis. It is the first time that ainylases were localized on starch without staining or adding a fluorescent probe at such high resolution. This technique presents a very high potential for imaging proteins in complex systems. Its sensitivity was demonstrated by the detection of GBSS (the granular bound starch synthase) at high recording times, GBSS being present at very low levels in maize starch granules. [ABSTRACT FROM AUTHOR]