Biochemical and genetic analyses of a novel γ-cyclodextrin glucanotransferase from an alkalophilic Bacillus clarkii 7364

抄録

A unique CGTase producing microorganism was successfully isolated from soil in Japan and identified as Bacillus clarkii, a kind of alkalophilic bacterium. The CGTase from this bacterium was purified by affinity chromatography on a γ-CD-immobilized column. The purified enzyme converted pre-gelatinized potato starch into CDs and the majority of the CDs product was γ-form. This property is quite unique and thus, we named this enzyme as γ-CGTase. The entire gene sequence amplified by PCR was determined and cloned into Escherichia coli. The comparison of the deduced amino acid sequence of γ-CGTase with those of other known CGTases that show different product specificities revealed the importance of subsites -3 and -7 for its preferential γ-cyclization activity.