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

Abstract

Each of the six and five positional isomers of 2 n - and 6 n-O-α- d- galactopyranosyl-6 1-O-α- d- glucopyranosyl-cyclomaltohexaose (α-cyclodextrin, αCD; 2 n : n = 1–6, 6 n : n = 2–6), which were produced from 6-O-α- d- glucopyranosyl-α CD and melibiose by transgalactosylation with coffee bean α-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.