EC - 1,4-α-glucan branching enzyme

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IntEnz Enzyme Nomenclature


Accepted name:
1,4-α-glucan branching enzyme
Other names:
α-glucan-branching glycosyltransferase
amylose isomerase
branching enzyme
branching glycosyltransferase
enzymatic branching factor
enzyme Q
glucosan transglycosylase
glycogen branching enzyme
plant branching enzyme
starch branching enzyme
amylo-(1,4 to 1,6)transglucosidase
1,4-α-D-glucan:1,4-α-D-glucan 6-α-D-(1,4-α-D-glucano)-transferase
Systematic name:
(1→4)-α-D-glucan:(1→4)-α-D-glucan 6-α-D-[(1→4)-α-D-glucano]-transferase



Converts amylose into amylopectin. The accepted name requires a qualification depending on the product, glycogen or amylopectin, e.g. glycogen branching enzyme, amylopectin branching enzyme. The latter has frequently been termed Q-enzyme.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0003844 , GO:0102752
CAS Registry Number: 9001-97-2
UniProtKB/Swiss-Prot: (296) [show] [UniProt]


  1. Barker, S.A., Bourne, E. and Peat, S.
    The enzymic synthesis and degradation of starch. Part IV. The purification and storage of the Q-enzyme of the potato.
    J. Chem. Soc. (Lond.) 1705-1711 (1949).
  2. Baum, H. and Gilbert, G.A.
    A simple method for the preparation of crystalline potato phosphorylase and Q-enzyme.
    Nature 171: 983-984 (1953).
  3. Hehre, E.J.
    Enzymic synthesis of polysaccharides: a biological type of polymerization.
    Adv. Enzymol. Relat. Subj. Biochem. 11: 297-337 (1951).
  4. Illingworth Brown, B. and Brown, D.H.
    α-1,4-Glucan:α-1,4-glucan 6-glycosyltransferase from mammalian muscle.
    Methods Enzymol. 8: 395-403 (1966).

[EC created 1961]