In enzymology, a 4-alpha-glucanotransferase (EC 2.4.1.25) is an enzyme that catalyzes a chemical reaction that transfers a segment of a 1,4-alpha-D-glucan to a new position in an acceptor carbohydrate, which may be glucose or a 1,4-alpha-D-glucan.
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases.
Other names in common use include disproportionating enzyme, dextrin glycosyltransferase, D-enzyme, debranching enzyme maltodextrin glycosyltransferase, amylomaltase, and dextrin transglycosylase.
[1][2] Studies of the enzyme from potato led to the discovery of cycloamylose.
[3] As of late 2007, 14 structures have been solved for this class of enzymes, with PDB accession codes 1CWY, 1ESW, 1FP8, 1FP9, 1K1W, 1K1X, 1K1Y, 1LWH, 1LWJ, 1TZ7, 1X1N, 2OWC, 2OWW, and 2OWX.