Literature summary for 2.4.1.B34 extracted from

Li, X.; Fei, T.; Wang, Y.; Zhao, Y.; Pan, Y.; Li, D.
Wheat starch with low retrogradation properties produced by modification of the GtfB enzyme 4,6-alpha-glucanotransferase from Streptococcus thermophilus (2018), J. Agric. Food Chem., 66, 3891-3898 .

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Application

Application	Comment	Organism
food industry	during the process of cooking wheat, semicrystallized chains of raw starch are hydrated into an amorphous form. After they have cooled for a sufficiently long period, linear molecules, amylose, and linear parts of amylopectin molecules expel water and rearrange into a more crystalline structure. This recrystallization, called retrogradation, often leads to the formation of hard and digestive enzyme-inaccessible textures in some wheat-based foods, resulting in poor sensory quality, short shelf life, and low consumer acceptance. After the GtfB-modified wheat starches are gelatinized and stored at 4°C for 1-2 weeks, their endothermic enthalpies are significantly lower than that of the control sample, indicating low retrogradation rates	Streptococcus thermophilus

Cloned(Commentary)

Cloned (Comment)	Organism
gene gtfB, recombinant expression of His-tagged truncated GtfB mutant in Escherichia coli strain BL21-CodonPlus-(DE3)	Streptococcus thermophilus

Protein Variants

Protein Variants	Comment	Organism
additional information	construction of a GtfB enzyme 4,6-alpha-glucanotransferase lacking 761 N-terminal amino acids	Streptococcus thermophilus

Organism

Organism	UniProt	Comment	Textmining
Streptococcus thermophilus	-	-	-
Streptococcus thermophilus NCC2408	-	-	-

Purification (Commentary)

Purification (Comment)	Organism
recombinant His-tagged truncated GtfB mutant 5.93fold from Escherichia coli strain BL21-CodonPlus-(DE3) by nickel affinity chromatography, ultrafiltration, and dialysis	Streptococcus thermophilus

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
additional information	purified recombinant truncated GtfB shows transglycosylation activities toward starch, resulting in branch points of alpha(1->6)-glycosidic linkages plus linear chains of alpha(1->4)-glycosidic linkages. GtfB catalyzes the transglycosylation reactions of amylose through cleaving alpha(1->4)-glycosidic linkage and synthesizing alpha(1->6)-glycosidic linkages. Usage of modified wheat starch, after the GtfB-modified wheat starches are gelatinized and stored at 4°C for 1-2 weeks, their endothermic enthalpies are significantly lower than that of the control sample, indicating low retrogradation rates. The GtfB-treated amylose is significantly different from the GtfB-untreated amylose, with more short-branch chains (DP1-4) of alpha(1->4)-glycosidic linkages. Amylose and amylopectin contents of natural and GtfB modified wheat starches, and conformational structure of GtfB-modified wheat starch, overview	Streptococcus thermophilus	?	-	-
additional information	purified recombinant truncated GtfB shows transglycosylation activities toward starch, resulting in branch points of alpha(1->6)-glycosidic linkages plus linear chains of alpha(1->4)-glycosidic linkages. GtfB catalyzes the transglycosylation reactions of amylose through cleaving alpha(1->4)-glycosidic linkage and synthesizing alpha(1->6)-glycosidic linkages. Usage of modified wheat starch, after the GtfB-modified wheat starches are gelatinized and stored at 4°C for 1-2 weeks, their endothermic enthalpies are significantly lower than that of the control sample, indicating low retrogradation rates. The GtfB-treated amylose is significantly different from the GtfB-untreated amylose, with more short-branch chains (DP1-4) of alpha(1->4)-glycosidic linkages. Amylose and amylopectin contents of natural and GtfB modified wheat starches, and conformational structure of GtfB-modified wheat starch, overview	Streptococcus thermophilus NCC2408	?	-	-

Subunits

Subunits	Comment	Organism
?	x * 180940, enzyme GtfB, sequence calculation	Streptococcus thermophilus

Synonyms

Synonyms	Comment	Organism
GtfB	-	Streptococcus thermophilus

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
40	-	recombinant enzyme	Streptococcus thermophilus

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
5	-	recombinant enzyme	Streptococcus thermophilus

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Release 2023.1 (January 2023)