Biochemical characterization of a highly thermostable amylosucrase from Truepera radiovictrix DSM 17093

In this study, a novel recombinant amylosucrase from Truepera radiovictrix DSM 17093 was characterized and found to produce α-glucans from sucrose. The enzyme showed maximum total and transglucosylation activities at pH 7.5 and maximum hydrolysis activity at pH 5.5. The optimum temperature for total, transglucosylation, and hydrolysis activities were determined to be 45, 45, and 50 °C, respectively. When the conversion of 100 mM sucrose was catalyzed at 35, 45, and 55 °C for 24 h, TR-ASase produced α-(1,4) glucans with average DPs of 59, 45, and 37, respectively. TR-ASase displayed more than 90% of its original activity after incubation at 55 °C for 5 h, which was much higher than that of all other reported ASases. Melting temperature determination and homology modeling were also adopted to analyze the extreme thermostability of this enzyme, TR-ASase.