hydrolysis of (1->4)-alpha-D-glucosidic linkage in 4-alpha-D-[(1->4)-alpha-D-glucanosyl]n trehalose to yield trehalose and (1->4)-alpha-D-glucan. Optimum pH is 5.0. Optimum temperature is 85 degrees Celsius. Glycan biosynthesis; trehalose biosynthesis. Homodimer. Belongs to the glycosyl hydrolase 13 family.