MetaCyc Compound Class: amylopectin

Superclasses: all carbohydratesa carbohydratea glycana polysaccharidea glucanstarch

Starch is a mixture of the two polymeric carbohydrates (polysaccharides) α-amylose and amylopectin.

α-Amylose contains up to several thousand glucosyl units linked almost exclusively in linear α(1->4) linkages, with very few branches of α(1->6) linkages. In amylopectin, on the other hand, branching is common, and occurs approximately every 24-30 glucose units.

α-Amylose accounts for 30% of starch, while amylopectin accounts for the other 70%.

amylopectin compound structure

Chemical Formula: C30H52O26

Molecular Weight: 828.72 Daltons

Monoisotopic Molecular Weight: 828.2746818438 Daltons


InChI: InChI=1S/C30H52O26/c31-1-6-11(35)13(37)19(43)28(50-6)55-24-9(4-34)52-27(21(45)16(24)40)48-5-10-25(56-29-20(44)14(38)12(36)7(2-32)51-29)17(41)22(46)30(53-10)54-23-8(3-33)49-26(47)18(42)15(23)39/h6-47H,1-5H2/t6-,7-,8-,9-,10-,11-,12-,13+,14+,15-,16-,17-,18-,19-,20-,21-,22-,23-,24-,25-,26+,27+,28-,29-,30-/m1/s1

Unification Links: ChemSpider:388347, HMDB:HMDB03255, KEGG:C00317, PubChem:439207

Standard Gibbs Free Energy of Change Formation (ΔfG in kcal/mol): -318.1018Inferred by computational analysis [Latendresse13]

Reactions known to consume the compound:

starch biosynthesis :
n amylopectin + α-amylose → n starch

starch degradation I :
starch → a linear malto-oligosaccharide

starch degradation II :
starch[chloroplast stroma] + n ATP[chloroplast stroma] + n H2O[chloroplast stroma] → a 6-phosphogluco-amylopectin[chloroplast stroma] + n AMP[chloroplast stroma] + n phosphate[chloroplast stroma]

starch degradation III , starch degradation IV :
starch[extracellular space] → a cyclodextrin[extracellular space]

starch degradation V :
starch[extracellular space] + H2O[extracellular space] → a maltodextrin(n)[extracellular space] + maltose[extracellular space] + D-glucopyranose[extracellular space]

Not in pathways:
starch + n H2O → n α-maltose
starch + n H2O → a long-linear glucan
starch + n H2O → a large-branched glucan
starch + H2O → maltose + glucose

starch degradation II :
a glucan[chloroplast stroma] + maltotriose[chloroplast stroma]a glucan[chloroplast stroma] + D-glucopyranose[chloroplast stroma]

Reactions known to produce the compound:

starch biosynthesis :
n (1,6)-α-D-glucosyl-(1,4)-α-glucan moderately branched[chloroplast stroma] → n amylopectin[chloroplast stroma]
n α-amylose → n amylopectin + n H2O

starch degradation II :
an exposed unphosphorylated, (α-1,6)-branched malto-oligosaccharide tail on amylopectin[chloroplast stroma] + n H2O[chloroplast stroma]amylopectin[chloroplast stroma] + n a linear malto-oligosaccharide[chloroplast stroma]
an exposed unphosphorylated, unbranched malto-oligosaccharide tail on amylopectin[chloroplast stroma] + n H2O[chloroplast stroma]amylopectin[chloroplast stroma] + maltose[chloroplast stroma]

cellulose and hemicellulose degradation (cellulolosome) :
a feruloyl-polysaccharide + H2O → ferulate + a polysaccharide + H+

In Reactions of unknown directionality:

Not in pathways:
a 6-phosphogluco-amylopectin + n H2O = amylopectin + n phosphate

Not in pathways:
n a 1,4-α-D-glucan = n starch + n H2O

This compound has been characterized as an alternative substrate of the following enzymes: pullulanase, α-1,4-glucan lyase

Revised 15-Mar-2013 by Caspi R, SRI International


Ball03: Ball SG, Morell MK (2003). "From bacterial glycogen to starch: understanding the biogenesis of the plant starch granule." Annu Rev Plant Biol 54;207-33. PMID: 14502990

Ball11: Ball S, Colleoni C, Cenci U, Raj JN, Tirtiaux C (2011). "The evolution of glycogen and starch metabolism in eukaryotes gives molecular clues to understand the establishment of plastid endosymbiosis." J Exp Bot 62(6);1775-801. PMID: 21220783

Buleon98: Buleon A, Colonna P, Planchot V, Ball S (1998). "Starch granules: structure and biosynthesis." Int J Biol Macromol 23(2);85-112. PMID: 9730163

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by Pathway Tools version 19.5 (software by SRI International) on Tue Dec 1, 2015, biocyc13.