Topographical and enzymatic characterization of amylases from the extremely thermophilic eubacterium Thermotoga maritima

AbstractThe hyperthermophilic cubacterium Thermotoga maritima uses starch as a substrate, without releasing amylase activity into the culture medium. The enzyme is associated with the ‘toga’. Its expression level is too low to allow the isolation of the pure enzyme. Using cycloheptaamylose and acarbose affinity chromatography and common chromatographic procedures, two enzyme fractions are obtained. They differ in specificity, pH-optimum, temperature dependence and stability. Substrate specificity and Ca2* dependence indicate α-, β- and gluco-amylase activity. Compared with α-amylase from Bacillus licheniformis (Tmax = 75°C), the amylasex from Thermotoga maritima show exceedingly high thermal stability with an upper temperature limit at 95°C. Significant turnover occurs only 70 and 100°C, i.e. in the range of viability of the microorganism