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discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
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MetaCyc Compound Class: α-amylose

Synonyms: an α-amylose

Superclasses: all carbohydrates a carbohydrate a glycan a polysaccharide a glucan a linear alpha-D-glucan a 1,4-alpha-D-glucan
all carbohydrates a carbohydrate a glycan a polysaccharide a glucan starch

Summary:
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%.

Reactions known to consume the compound:

starch biosynthesis :
ADP-α-D-glucose[chloroplast stroma] + n (1,4-α-D-glucosyl)(n)[chloroplast stroma] → ADP[chloroplast stroma] + n α-amylose[chloroplast stroma]
n α-amylose → n amylopectin + n H2O
n amylopectin + α-amylose → n starch

starch biosynthesis :
n a 1,4-α-D-glucan → a (1,6)-α-D-glucosyl-(1,4)-α-glucan highly branched + n H2O

Not in pathways:
a 1,4-α-D-glucan + H2O → a 1,4-α-D-glucan + maltose
a 1,4-α-D-glucan + n H2O → n a 1,4-α-D-glucan
a 1,4-α-D-glucan + n H2O → a 1,4-α-D-glucan + n maltotetraose
a 1,4-α-D-glucan + H2O → a 1,4-α-D-glucan + maltotriose
a 1,4-α-D-glucan + H2O → a 1,4-α-D-glucan + maltohexaose
(1,4-α-D-glucosyl)(n) + H2O → (1,4-α-D-glucosyl)(n-1) + α-D-glucose
a 1,4-α-D-glucan[periplasmic space] + n H2O[periplasmic space]a 1,4-α-D-glucan[periplasmic space] + maltohexaose[periplasmic space]

starch degradation I :
starch + n H2O → a long-linear glucan
starch + n H2O → a large-branched glucan

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]


starch + n H2O → n α-maltose
starch + H2O → maltose + glucose

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


a polysaccharide + H2O → an oligosaccharide

Reactions known to produce the compound:

cellulose and hemicellulose degradation (cellulolosome) :
a feruloyl-polysaccharide + H2O → ferulate + a polysaccharide + 2 H+

Not in pathways:
an N-acetyl-β-D-galactosalaminyl-[glycan] + H2O → a glycan + N-acetyl-β-D-galactosamine

Reactions known to both consume and produce the compound:

glycogen biosynthesis I (from ADP-D-Glucose) :
a 1,4-α-D-glucan ↔ a glycogen
ADP-α-D-glucose + (1,4-α-D-glucosyl)(n) ↔ ADP + (1,4-α-D-glucosyl)(n+1)

starch biosynthesis :
ADP-α-D-glucose + (1,4-α-D-glucosyl)(n) ↔ ADP + (1,4-α-D-glucosyl)(n+1)

Not in pathways:
(1,4-α-D-glucosyl)(n) + phosphate ↔ (1,4-α-D-glucosyl)(n-1) + α-D-glucose 1-phosphate

In Reactions of unknown directionality:

Not in pathways:
a 1,4-α-D-glucan = a cyclodextrin
n a 1,4-α-D-glucan = n starch + n H2O
sucrose + (1,4-α-D-glucosyl)(n) = D-fructofuranose + (1,4-α-D-glucosyl)(n+1)
(1,4-α-D-glucosyl)(n) = (1,4-α-D-glucosyl)(n-1) + a (1,6)-α-D-glucosyl-(1,4)-α-glucan
a 1,4-α-D-glucan + a 1,4-α-D-glucan = a 1,4-α-D-glucan + a 1,4-α-D-glucan
α-maltose 1-phosphate + (1,4-α-D-glucosyl)(n-1) = (1,4-α-D-glucosyl)(n+1) + phosphate
a nucleoside diphosphate-glucose + a 1,4-α-D-glucan = a nucleoside diphosphate + a 1,4-α-D-glucan
(1,4-α-D-glucosyl)(n) + (1,6-α-D-glucosyl)(m) = (1,4-α-D-glucosyl)(n-1) + (1,6-α-D-glucosyl)(m+1)


n a 1,4-α-D-glucan = n starch + n H2O


a linear α-D-glucan + sucrose = an alternan
a linear α-D-glucan = n 1,5-anhydro-D-fructose + β-D-glucose
a linear α-D-glucan + ATP + H2O = [phospho-α-glucan] + AMP + phosphate + 2 H+

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


Report Errors or Provide Feedback
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 SRI International Pathway Tools version 18.5 on Tue Nov 25, 2014, BIOCYC14B.