A novel method to produce branched alpha-cyclodextrins: Pullulanase-glucoamylase-mixed method
1997
Watanabe, N. (Amano Pharmaceutical Co. Ltd., Nishiharu, Aichi (Japan)) | Yamamoto, K. | Tsuzuki, W. | Oya, T. | Kobayashi, S.
We have developed a novel method to produce 6-O-alpha-D-glucosyl-alpha-cyclodextrins (G1-alpha-CDs) such as G1-alpha-CD and 61,6n-di-O-alpha-D-glucosyl-alpha-CDs ((G1)2-alpha-CDs). This method is a combined one-step process composed of the condensation of maltose (G2) and alpha-CD by reverse-synthesis with pullulanase and hydrolysis of intermediate 6-O-alpha-maltosyl-alpha-CD (G2-alpha-CD) by glucoamylase. In a comparison of substrate specificities for three glucoamylases, A. niger glucoamylase had the highest specificity toward G2-alpha-CD. The yield of G1-alpha-CDs could be increased using this method with A. niger glucoamylase, which suggests that the equilibrium of the condensation reaction with pullulanase slid to G2-alpha-CD synthesis as a result of the conversion of G2-alpha-CD into G1-alpha-CD by glucoamylase. A maximum branched ratio of lineal 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 G2 to CD (G2/CD)i, and enzyme unit ratio of pullulanase to glucoamylase (Up/Ug)
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