6³-α-D-Glucosyl-maltotriose

In recent research on the hydrolysis of ((1→4)-α-D and (1→6)-α-D linkages in starch by glucoamylases (EC 3.2.1.3.), model oligosaccharides, including 6³-α-D-glucosylmaltotriose, were required. The preparation of this tetrasaccharide by the published methods is tedious and the yields are small (<1%). A simple preparation of pure 6³-α-D-gluscosylmaltotriose in good yield is now described. It was considered that 6³-α-D-glucosylmaltotriose could be prepared by beta-amylolysis of 6³-α-D-maltotriosylmaltotriose. This hexasaccharide, which was present in maximum amount when pullulan was hydrolysed to ~50% by pullulanase, was completely converted into a mixture of 6³-α-D-glucosylmaltotriose and maltose by beta-amylase (4 U/mg of hexasaccharide) at 37°C and pH 5 for 1 h.

Microarrays are powerful tools for high throughput analysis, and hundreds or thousands of molecular interactions can be assessed simultaneously using very small amounts of analytes. Nucleotide microarrays are well established in plant research, but carbohydrate microarrays are much less established, and one reason for this is a lack of suitable glycans with which to populate arrays. Polysaccharide microarrays are relatively easy to produce because of the ease of immobilizing large polymers noncovalently onto a variety of microarray surfaces, but they lack analytical resolution because polysaccharides often contain multiple distinct carbohydrate substructures. Microarrays of defined oligosaccharides potentially overcome this problem but are harder to produce because oligosaccharides usually require coupling prior to immobilization. We have assembled a library of well characterized plant oligosaccharides produced either by partial hydrolysis from polysaccharides or by de novo chemical synthesis. Once coupled to protein, these neoglycoconjugates are versatile reagents that can be printed as microarrays onto a variety of slide types and membranes. We show that these microarrays are suitable for the high throughput characterization of the recognition capabilities of monoclonal antibodies, carbohydrate-binding modules, and other oligosaccharide-binding proteins of biological significance and also that they have potential for the characterization of carbohydrate-active enzymes.