Enzymatic synthesis of manno- and heteromanno-oligosaccharides using \#a\-mannosidases: a comparative study of linkage-specific and non-linkage specific enzymes

Two \#a\-mannosidase enzymes and an \#a\-1,2-mannosidase enzyme were compared for their ability to synthesise hetero-oligosaccharides by the equilibrium approach (condensation reaction). A panel of disaccharide acceptors was tested and product yields and product spectra determined. The choice of enzyme had a significant influence on product yield. Most of the enzyme/substrate combinations tested gave 1 \-R\ 6 linked manno-oliogosaccharides as the principal product. Mannose was linked to lactose, cellobiose and lactulose by both 1 \-R\ 3 and 1 \-R\ 6 linkages in ratios that depended upon the enzyme used. Homo-oligosaccharide (mannotriose) formation was found in all but one of the enzyme/substrate combinations tested and, in the case of the \#a\-1,2-mannosidase, the structure of the mannotrioses depended on the acceptor used. Formation of hetero-oligosaccharides over homo-oligosaccharides could be favoured by use of low mannose:acceptor ratios. (Original abstract - amended)