Purification and characterization of an acid trehalase from Acidobacterium capsulatum

We purified an acid trehalase (EC 3.2.1.28, α,α′-trehalose glucohydrolase) from an acidophilic bacterium, Acidobacterium capsulatum. The enzyme was homogeneous based on polyacrylamide gel electrophoresis, and was composed of a single polypeptide chain with a molecular mass of 57 kDa. Maximum trehalase activity was observed at pH 2.5. The acid trehalase exhibited an apparent K_m of 1.0 mM for trehalose at 30°C and pH 3.0. The trehalase was located in the periplasmic space. The activity of the enzyme was activated by 1.0 mM MnCl₂ or CoCl₂, and inhibited by 1.0 mM PbCl₂, HgCl₂, NiCl₂, p-chloromercuribenzoate, N-ethylmaleimide, monoiodoacetate, or EDTA. The enzyme showed high specificity for trehalose. It was found that an equimolar mixture of α-D-glucose and β-D-glucose was formed on hydrolysis of trehalose by the trehalase.