Samantekt:
Trehalases play a central role in the metabolism of trehalose and can be found in a wide variety of organisms. A periplasmic trehalase (a,a-trehalose glucohydrolase, EC 3.2.1.28) from the thermophilic bacterium Rhodothermus marinus was purified and the respective encoding gene was identified, cloned and overexpressed in Escherichia coli. The recombinant trehalase is a monomeric protein with a molecular mass of 59 kDa.
Maximum activity was observed at 88C and pH 6.5. The recombinant trehalase exhibited a Km of 0.16 mM and a Vmax of 81 lmol of trehalose (min)1 (mg of protein)1 at the optimal temperature for growth of R. marinus (65C) and pH 6.5. The enzyme was highly specific for
trehalose and was inhibited by glucose with a Ki of 7 mM. This is the most thermostable trehalase ever characterized. Moreover, this is the first report on the identification and characterization of a trehalase from a
thermophilic bacterium.