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Literature summary for 3.2.1.2 extracted from

  • Kaplan, F.; Sung, D.Y.; Guy, C.L.
    Roles of beta-amylase and starch breakdown during temperature stress (2006), Physiol. Plant., 126, 120-128.
No PubMed abstract available

Activating Compound

Activating Compound Comment Organism Structure
additional information cold stress activates the chloroplastic isozyme by 5fold at 3°C Arabidopsis thaliana

Cloned(Commentary)

Cloned (Comment) Organism
-
Solanum tuberosum

Protein Variants

Protein Variants Comment Organism
additional information chloroplast-localized enzyme downregulation by expression of antisense mRNA results in a starch-excess phenotype in leaves compared to wild-type plants Solanum tuberosum
additional information knockout plants of palstidic isozymes BMY6 and BMY8/CT-BMY leads to a starch-excess phenotype in leaves Arabidopsis thaliana

Localization

Localization Comment Organism GeneOntology No. Textmining
chloroplast stroma of mesophyll cell chloroplasts Solanum tuberosum 9507
-
chloroplast stroma of mesophyll cell chloroplasts Glycine max 9507
-
chloroplast stroma of mesophyll cell chloroplasts Arabidopsis thaliana 9507
-
chloroplast stroma
-
Solanum tuberosum 9570
-
chloroplast stroma
-
Glycine max 9570
-
chloroplast stroma
-
Arabidopsis thaliana 9570
-
cytosol
-
Arabidopsis thaliana 5829
-
vacuole
-
Arabidopsis thaliana 5773
-

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
additional information Arabidopsis thaliana plants mechanism of cold adaptation, enzyme regulation by phytohormones, light, and by abiotic stess, e.g. by osmotic, cold, salt, and drought stress, the enzyme is also regulated by the circadian clock, detailed overview ?
-
?
starch + H2O Solanum tuberosum
-
maltose + ?
-
?
starch + H2O Glycine max
-
maltose + ?
-
?
starch + H2O Arabidopsis thaliana role of beta-amylase in starch breakdown during temperature stress, product maltose acts as a cryoprotectant and precursor of soluble sugar metabolism, overview maltose + ?
-
?

Organism

Organism UniProt Comment Textmining
Arabidopsis thaliana
-
several isozymes
-
Glycine max
-
-
-
Hordeum vulgare
-
-
-
Solanum tuberosum
-
-
-

Posttranslational Modification

Posttranslational Modification Comment Organism
proteolytic modification BMY is stored in seeds bound to starchy endosperm possibly through S-S bridges, during germination the enzyme is released by proteolytic cleavage resulting in a smaller enzyme form, the uncleaved enzyme form shows reduced activity Hordeum vulgare

Reaction

Reaction Comment Organism Reaction ID
(alpha-D-glucopyranosyl-(1-4))n-alpha-D-glucopyranose + H2O = (alpha-D-glucopyranosyl-(1-4))n-2-alpha-D-glucopyranose + alpha-D-glucopyranosyl-(1-4)-beta-D-glucopyranose general acid-base catalytic reaction mechanism Arabidopsis thaliana
(alpha-D-glucopyranosyl-(1-4))n-alpha-D-glucopyranose + H2O = (alpha-D-glucopyranosyl-(1-4))n-2-alpha-D-glucopyranose + alpha-D-glucopyranosyl-(1-4)-beta-D-glucopyranose roles of Glu186 and Glu380 as general acid and general base catalyst in the catalytic reaction, reaction mechanism involving residue T342 Glycine max

Source Tissue

Source Tissue Comment Organism Textmining
endosperm BMY is stored in seeds bound to starchy endosperm possibly through S-S bridges, during germination the enzyme is released by proteolytic cleavage resulting in a smaller enzyme form Hordeum vulgare
-
leaf
-
Solanum tuberosum
-
leaf
-
Glycine max
-
mesophyll
-
Solanum tuberosum
-
mesophyll
-
Glycine max
-
mesophyll
-
Arabidopsis thaliana
-
seed BMY is stored in seeds bound to starchy endosperm possibly through S-S bridges, during germination the enzyme is released by proteolytic cleavage resulting in a smaller enzyme form Hordeum vulgare
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
additional information plants mechanism of cold adaptation, enzyme regulation by phytohormones, light, and by abiotic stess, e.g. by osmotic, cold, salt, and drought stress, the enzyme is also regulated by the circadian clock, detailed overview Arabidopsis thaliana ?
-
?
starch + H2O
-
Solanum tuberosum maltose + ?
-
?
starch + H2O
-
Glycine max maltose + ?
-
?
starch + H2O
-
Arabidopsis thaliana maltose + ?
-
?
starch + H2O role of beta-amylase in starch breakdown during temperature stress, product maltose acts as a cryoprotectant and precursor of soluble sugar metabolism, overview Arabidopsis thaliana maltose + ?
-
?

Synonyms

Synonyms Comment Organism
BMY
-
Hordeum vulgare
BMY
-
Solanum tuberosum
BMY
-
Glycine max
BMY
-
Arabidopsis thaliana

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
1260 1280 starch pH 5.4-6.0, major isozyme Glycine max

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
5.4 6
-
Glycine max