Cyclodextrin glycosyltransferase (CGTase) from the thermophilic anaerobe Thermoanaerobacter sp. 5K was
purified and characterized. The enzyme was purified with ammonium sulfate precipitation followed by α-CD-bound,
epoxy-activated Sepharose 6B affinity chromatography. Molecular weight of the purified enzyme was 70.6 kDa. The
enzyme had optimal activity at 80-90°C and retained greater than 90% activity between 75°C and 95°C. Optimal pH
activity was observed at 7.0, with at least 50% activity between pH 4.0 and 9.0. It was highly stable at elevated
temperature, with no loss of activity after incubation at 80°C for 4 hours or at 90°C for 30 min. Km and Vmax values were
0.222 mg/mL and 0.206 mg β-CD/mL/min, respectively, with soluble starch. Amino acid composition of the enzyme was
deduced from the sequence of the cloned CGTase gene. The mature enzyme has a deduced molecular weight of 75.63 kDa
and contains residues conserved in the CGTase class of amylase enzymes.
Keywords: Anaerobe; cyclodextrin glycosyltransferase, cyclodextrin, Thermoanaerobacter, thermophilic extremozyme.
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