Isolation by HPLC of the positional isomers of heterogeneous doubly branched cyclomaltohexaose having one alpha-D-galactosyl and one alpha-D-glucosyl side chain and determination of their structures by enzymatic degradation.

Each of the six and five positional isomers of 2n- and 6n-O-alpha-D-galactopyranosyl-6(1)-O-alpha-D-glucopyranosyl-cyclomalt ohexaose (alpha-cyclodextrin, alpha CD; 2n: n = 1-6, 6n: n = 2-6), which were produced from 6-O-alpha-D-glucopyranosyl-alpha CD and melibiose by transgalactosylation with coffee bean alpha-galactosidase, were isolated by high-performance liquid chromatography (HPLC) on a reversed-phase column and a graphitized carbon column. The structures of those isomers were elucidated by analyses of enzymatic degradation products with cyclomaltodextrin glucanotransferase and glucoamylase.