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Literature summary extracted from

  • Barends, T.R.; Bultema, J.B.; Kaper, T.; van der Maarel, M.J.; Dijkhuizen, L.; Dijkstra, B.W.
    Three-way stabilization of the covalent intermediate in amylomaltase, an alpha-amylase-like transglycosylase (2007), J. Biol. Chem., 282, 17242-17249.
    View publication on PubMed

Cloned(Commentary)

EC Number Cloned (Comment) Organism
2.4.1.25 expression of the His-tagged enzyme in Escherichia coli strain BL21(DE3) Thermus thermophilus

Crystallization (Commentary)

EC Number Crystallization (Comment) Organism
2.4.1.25 purified recombinant enzyme, hanging drop vapour diffusion method, 0.003 ml of protein solution containing 10 mM MES-NaOH, pH 6.5, with 1 mM dithiothreitol is mixed with 0.001-0.003 ml of reservoir solution containing 0.4-0.8 M sodium malonate, pH 5.6, and 1 mM dithiothreitol, equilibration against reservoir solution at room temperature, 1 week, for enzyme-acarbose complexing the crystals are soaked in 0.5 ml of 0.8 M sodium malonate, pH 5.6, with 5 mg/ml acarbose and with or without and 4-deoxyglucose, for 30 min, X-ray diffraction structure determination and analysis at 1.9-2.5 A resolution Thermus thermophilus

Protein Variants

EC Number Protein Variants Comment Organism
2.4.1.25 E758Q the mutant shows highly reduced activity compared to the wild-type enzyme Thermus thermophilus
2.4.1.25 additional information the deletion mutant DELTAN130 is unable to use glycogen but has high disproportionating activity with maltodextrins Thermus thermophilus

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.4.1.25 additional information
-
 additional information initial rate kintics Thermus thermophilus

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
2.4.1.25 additional information Thermus thermophilus amylomaltases are capable of the synthesis of large cyclic glucans and the disproportionation of oligosaccharides ?
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
2.4.1.25 Thermus thermophilus O87172
-
-

Purification (Commentary)

EC Number Purification (Comment) Organism
2.4.1.25 recombinant His-tagged enzyme from Escherichia coli strain BL21(DE3) by heat treatment and nickel affinity chromatography, removal of the His-tag through cleavage with bovine thrombin Thermus thermophilus

Reaction

EC Number Reaction Comment Organism Reaction ID
2.4.1.25 maltononaose + maltotriose = maltoundecaose + D-glucose reaction mechanism and catalytic cycle, the catalytic nucleophile changes conformation dramatically during the reaction, Gln256 on the 250s loop is involved in orienting the substrate in the +1 site. The absence of a suitable base in the covalent intermediate structure explains the low hydrolysis activity, overview Thermus thermophilus
a

Specific Activity [micromol/min/mg]

EC Number Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
2.4.1.25 0.0027
-
 mutant E758Q Thermus thermophilus
2.4.1.25 5.19
-
 wild-type enzyme Thermus thermophilus

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.4.1.25 additional information amylomaltases are capable of the synthesis of large cyclic glucans and the disproportionation of oligosaccharides Thermus thermophilus ?
-
 ?
2.4.1.25 additional information glucose transfer/production using maltose and glycogen. Wild-type DPE2 can bind to starch and glycogen has very little, if any, ability to dissociate DPE2 from the starch pellet Thermus thermophilus ?
-
 ?

Synonyms

EC Number Synonyms Comment Organism
2.4.1.25 alpha-amylase-like transglycosylase
-
 Thermus thermophilus
2.4.1.25 amylomaltase
-
 Thermus thermophilus
2.4.1.25 More amylomaltases are glycosyl hydrolases belonging to glycoside hydrolase family 77 Thermus thermophilus