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Literature summary for 3.2.1.2 extracted from

  • Kang, Y.N.; Adachi, M.; Utsumi, S.; Mikami, B.
    The roles of Glu186 and Glu380 in the catalytic reaction of soybean beta-amylase (2004), J. Mol. Biol., 339, 1129-1140.
    View publication on PubMed
Search for more literature for 3.2.1.2

Cloned(Commentary)

Cloned (Comment) Organism
expression of wild-type and mutants in Escherichia coli strains JM109 and JM105 Glycine max

Crystallization (Commentary)

Crystallization (Comment) Organism
purified recombinant mutant enzymes, mutant enzyme E186Q in complex with substrate maltopentaose, and mutant enzyme E380Q in complex with product maltose, hanging drop vapour diffusion method, 20 mg/ml protein in 45-50% w/v ammonium sulfate, 0.1 M sodium acetate, pH 5.4, 1 mM EDTA, and 18 mM 2-methyl-2,4-pentanediol, equilibration against 1 ml mother liquor, 4°C, soaking of crystals in 30 mM ligand solution, cryoprotection of crystals with 30% v/v glycerol in crystallization solution, X-ray diffraction structure determination and analysis at 1.6 and 1.9 A resolution, respectively, active site structure modelling Glycine max

Protein Variants

Protein Variants Comment Organism
E186Q site-directed mutagenesis, mutation of catalytic residue, the mutant shows 16000fold decreased activity compared to the wild-type enzyme Glycine max
E380Q site-directed mutagenesis, mutation of catalytic residue, the mutant shows 37000fold decreased activity compared to the wild-type enzyme Glycine max

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
1.94
-
 maltopentaose pH 5.4, 37°C, wild-type enzyme Glycine max
2.02
-
 maltopentaose pH 5.4, 37°C, mutant E380Q Glycine max
2.15
-
 maltopentaose pH 5.4, 37°C, mutant E186Q Glycine max

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
amylopectin + H2O Glycine max
-
 maltose + ?
-
 ?

Organism

Organism UniProt Comment Textmining
Glycine max P10538
-
-

Purification (Commentary)

Purification (Comment) Organism
recombinant wild-type and mutants from Escherichia coli Glycine max

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 roles of Glu186 and Glu380 as general acid and general base catalyst in the catalytic reaction, substrate binding and reaction mechanism Glycine max
a

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
additional information
-
-
 Glycine max

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
amylopectin + H2O
-
 Glycine max maltose + ?
-
 ?
amylopectin + H2O from potato Glycine max maltose + ?
-
 ?
maltopentaose + H2O substrate/product binding structure, sugar subsite conformations, overview Glycine max 2 maltose + D-glucose
-
 ?

Subunits

Subunits Comment Organism
More structure analysis, intramolecular hydrogen bond interactions Glycine max

Synonyms

Synonyms Comment Organism
SBA
-
 Glycine max

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
37
-
 assay at Glycine max

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
0.034
-
 maltopentaose pH 5.4, 37°C, mutant E380Q Glycine max
0.08
-
 maltopentaose pH 5.4, 37°C, mutant E186Q Glycine max
1280
-
 maltopentaose pH 5.4, 37°C, wild-type enzyme Glycine max

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
5.4
-
 assay at Glycine max