Intercoversion Reactions Among Cyclodextrin Homologs by Cyclodextrin Glycosyl Transferase

초록

The reaction characteristics of cyclodextrin glycosyltransferase(CGTase, EC 2.4.1.19) for the production and interconversion of cyclodextrin homologues(CDs) were studied. Interconversions among CDs are resulted from the three reactions of CGTase, coupling, disproportionation and cyclization. Though the major product of the enzyme from Bacillus macerans(Amano Co.) used in this experiment is b-CD, this enzyme produces a-CD mainly at the beginning, and converts a-CD into b- CD, mostly, and g-CD. The conversion rate of a-CD to other CDs was the highest among the homologues, when each was used as a substrate separately. The conversion rate was in the order of a-, g- and b-CD. Based on these results, a-CD is considered to be an intermediate molecule in the production of CDs, the reaction characteristics of which are regarded to be affected by the solubilities and the sizes of the homologues. The effects of linear oligosaccharides as byproducts on the interconversion are under investigation.