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A cyclodextrin glucanotransferase (CGTase) was successively purified by ammonium sulphate precipitation, and affinity chromatography on α-CD (epoxy)-Sepharose 6B column. The specific activity of the CGTase was increased approximately 2200-fold, from 8.43U/mg protein to 18,866U/mg protein. SDS-PAGE showed that the purified CGTase was homogeneous and the molecular weight of the purified CGTase was about 75kDa. The molecular weight of the enzyme that was estimated by gel filtration under native condition was 79kDa. This has indicated that Bacillus sp. G1 CGTase is a monomeric protein. The isoelectric point (pI) of the enzyme was about 8.8. Characterization of the enzyme exhibited optimum pH and temperature of 6.0 and 60°C, respectively. The enzyme was stable from pH 7.0 to 9.0 and retained its high activity up to 60°C. However, in the presence of 20mM Ca²⁺, the purified CGTase is able to …