Purification and characterization of cyclodextrin glucanotransferase from an alkalophilic bacterium of Taiwan.

Abstract

From some soil of Taipei, we isolated a strain of alkalophilic bacterium, Bacillus sp. HA3-3-2, that was capable of producing sufficient amounts of Cyclodextrin glucanotransferase (CGTase) in the culture broth. This enzyme was successively purified by ammonium sulfate fractionation, Sephadex column chromatography and DEAE-cellulose column chromatography. The final preparation thus obtained showed only a single band, when assayed by polyacrylamide disc gel electrophoresis and SDS-polyacrylamide gel electrophoresis. The molecular weight was estimated as 68, 000 by SDS-polyacrylamide gel electrophoresis. The purified enzyme possessed its maximum cyclodextrin-forming activity in the pH range of 6.5 to 8.0, and was stable between pH 6 and 11. This enzyme was not inhibited by typical bio-specific inhibitors, e.g., phenylmethylsulfonyl fluoride (PMSF), p-chloromercuribenzoate (PCMB) and ethylenediaminetetraacetic acid (EDTA). On the basis of its properties, this enzyme seems to be a novel CGTase.