In enzymology, an alpha,alpha-trehalose phosphorylase (configuration-retaining) () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are alpha,alpha-trehalose and phosphate, whereas its two products are alpha-D-glucose and alpha-D-glucose 1-phosphate.
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is alpha,alpha-trehalose:phosphate alpha-D-glucosyltransferase. This enzyme is also called trehalose phosphorylase[ambiguous].