Effects of the polyhistidine tag on kinetics and other properties of trehalose synthase from Deinococcus geothermalis.

Two recombinant trehalose synthases from Deinococcus geothermalis (DSMZ 11300) were compared. A significant influence of the artificial polyhistidine tag was observed in protein constitution. The recombinant trehalose synthase from D. geothermalis with His₆-tag has a higher Km value of 254 mM, in comparison with the wild-type trehalose synthase (Km 170 mM), and displayed a lower activity of maltose conversion when compared to the wild type. Moreover, differences in properties like temperature, pH, thermal- and pH-stability were observed. Presence of the histidine tag caused a decrease of thermal resistance in case of trehalose synthase with His₆-tag. These data confirmed a suggestion that the introduction of the histidine domain produces in some seldom cases undesirable changes in the protein.