Action of a Thermostable Trehalose Synthase from Thermus aquaticus on Sucrose

A thermostable trehalose synthase from Thermus aquaticus ATCC 33923, which catalyzes the interconversion between maltose and trehalose by intramolecular transglucosylation, converted sucrose into trehalulose (1-O-α-d-glucopyranosyl-d-fructose). The trehalulose-forming activity of the enzyme was very low compared with that of maltose and trehalose. Kinetic studies showed that sucrose competitively inhibited the interconversion activity between maltose and trehalose. Consequently, these three substrates, maltose, trehalose, and sucrose, are thought to bind the same active site of trehalose synthase.