A Novel Method to Produce Branched α-Cyclodextrins : Pullulanase-Glucoamylase-Mixed Method

概要

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We have developed a novel method to produce 6-O-α-D-glucosly-α-cyclodextrins (G_1-α-CDs) such as G_1-α-CD and 6^1,6^n-di-O-α-D-glucosly-α-CDs ((G_1)_2-α-CDs). This method is a combined one-step process composed of the condensation of maltose (G_2) and α-CD by reverse-synthesis with pululanase and hydrolysis of intermediate 6-O-α-maltosyl-α-CD (G_2-α-CD) by glucoamilase. In a comparison of substrate specificities for three glucoamylases (from Aspergillus niger, Rhizopus niveus, and Endomyces sp.), A. niger glucoamylase had the highest specificity toward G_2-α-CD. The yield of G_1-α-CDs could be increased using this method with A. niger glucoamylase, which suggests that the equilibrium of the condensation reacton with pullulanase slid to G_2-α-CD synthesis as a result of the conversion ofG_2-α-CD into G_1-α-CD by glucoamylase. A maximum branched ratio of final products was 69% using this method, whereas that by a conventional method was only 60%. THe branched ratio varied under several operational conditions such as total substrate content, initial molar ratio of G_2 to CD (G_2/CD)i, and enzyme unit ratio of pullulansae to glucoamylase (Up/Ug).
社団法人日本生物工学会の論文
1997-01-25