In enzymology, an amylosucrase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are sucrose and (1,4-alpha-D-glucosyl)n, whereas its two products are D-fructose and (1,4-alpha-D-glucosyl)n+1.
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is sucrose:1,4-alpha-D-glucan 4-alpha-D-glucosyltransferase. Other names in common use include sucrose-glucan glucosyltransferase, and sucrose-1,4-alpha-glucan glucosyltransferase. This enzyme participates in starch and sucrose metabolism.
As of late 2007, 10 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , , and .