Chemoenzymatic synthesis of 6 omega-S-alpha-D-glucopyranosyl-6 omega-thiomaltooligosaccharides: their binding to Aspergillus niger glucoamylase G1 and its starch-binding domain
1995
Apparu, C. | Driguez, H. | Williamson, G. | Svensson, B.
A coupling reaction of cyclodextrin glucosyltransferase (CGTase) with glucose and 6-deoxy-6-iodo-cyclomaltoheptaose (1), in the presence of glucoamylase, followed by acetylation, led to a convenient synthesis of acetylated 6(III)-deoxy-6(III)-iodo-maltotriose (2) and 6(IV)-deoxy-6(IV)-iodo-maltotetraose (3). Nucleophilic displacement of the iodine atom of these protected maltotriose and maltotetraose analogs by the activated form of 2,3,4,6-tetra-O-acetyl-1-S-acetyl-1-thio-alpha-D-glucose (4) afforded peracetylated 6(III)-S-alpha-D-glucopyranosyl-6(III)-thiomaltotriose (5) and 6(IV)-S-alpha-D-glucopyranosyl-6(IV)-thiomaltotetraose (C) in high yield. The interaction of OH-free tetra- and penta-saccharides (7 and 8) with both glucoamylase G1 from Aspergillus niger as well as its isolated starch-binding domain fragment were studied by UV difference spectroscopy. It was found that the starch-binding domain has higher affinity for 7 and 8 than for maltotetraose and maltopentaose.
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