Construction of the fusion enzymes CGTΔE-CBMAmy and CGT-CBMAmy. (A) The carbohydrate-binding module (CBM) from alkaliphilic A. amylolytica α-amylase (CBMAmy) was fused to the carboxyl terminus of P. macerans cyclodextrin glycosyltransferase (CGTase) or was used to replace the E domain of P. macerans CGTase using overlapping extension PCR. (B) Amino acid composition of the fusion proteins. (C) Agarose gel electrophoresis of the overlapping extension PCR. M1, DL5000 DNA marker; M2, DL2000 DNA marker; lane 1, the gene fragment of domains A to D of CGTase; lanes 2 and 5, the gene fragment of CBMAmy; lane 3, the gene fragment of the fusion gene coding for CGTΔE-CBMAmy; lane 4, the gene fragment of CGTase; lane 6, the gene fragment of the fusion gene coding for CGT-CBMAmy.