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Updated: Jan 27, 2026

A New Screening Method for the Directed Evolution of Thermostable Bacteriolytic Enzymes
Published on: November 7, 2012
Thermostable CITase from Thermoanaerobacter thermocopriae shows negative cooperativity
So-Jin Yang1, Su-Jeong Choi1, Bo-Ram Park2
1Department of Food Science and Technology, Chonnam National University, Gwangju, 61186, Republic of Korea.
Objective:
The biochemical properties of a putative thermostable cycloisomaltooligosaccharide (CI) glucanotransferase gene from Thermoanaerobacter thermocopriae were determined using a recombinant protein (TtCITase) expressed in Escherichia coli and purified to a single protein.
Results:
The 171-kDa protein displayed maximum activity at pH 6.0, and enzyme activity was stable at pH 5.0-11.0. The optimal temperature was 60 °C in 1 h incubation, and thermal stability of the protein was 63% at 60 °C for 24 h. TtCITase produced CI-7 to CI-17, as well as CI-18, CI-19, and CI-20, which are relatively large CIs. Additionally, an unusual kinetic feature of TtCITase was its negative cooperative behavior in the dextran T2000 cleavage reaction.
Conclusions:
Based on our results, TtCITase can be applied to produce relatively large CIs at high temperature.
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