Wheat Starch with Low Retrogradation Properties Produced by Modification of the GtfB Enzyme 4,6-α-Glucanotransferase from Streptococcus thermophilus

Abstract

A GtfB enzyme 4,6-α-glucanotransferase from Streptococcus thermophilus lacking 761 N-terminal amino acids was heterologously expressed in Escherichia coli. Purified S. thermophilus GtfB showed transglycosylation activities toward starch, resulting in branch points of (α1→6)-glycosidic linkages plus linear chains of (α1→4)-glycosidic linkages. After wheat starch was modified at a rate of 0.1 g/mL by 1-4 U/g starch GtfB at pH 6.0 and 40 °C for 1 h, the weight-averaged molecular weight decreased from 1.70 × 10 g/mol to 1.21 × 10 to 3.41 × 10 g/mol, the amylose content decreased from 22.07 to 16.34-17.11%, and that of amylopectin long-branch chains decreased from 26.4 to 10.25-15.64% ( P < 0.05). After the GtfB-modified wheat starches were gelatinized and stored at 4 °C for 1-2 weeks, their endothermic enthalpies were significantly lower than that of the control sample ( P < 0.05), indicating low retrogradation rates.

Structural factors governing starch digestion and glycemic responses and how they can be modified by enzymatic approaches: A review and a guide

“…Such modification evidently increases the branching density and increases the relative content of short AP chains (DP < 12). It also lowers the extent of retrogradation upon storage at 4 • C (Li, Fei, et al, 2018). Unfortunately, the impact on starch digestion has not been studied.…”

Response-Related Factors of Bone Marrow-Derived Mesenchymal Stem Cells Transplantation in Patients with Alcoholic Cirrhosis

“…MMP-2 and MMP-9, which are key factors in cancer metastasis, were affected by RBP4 overexpression. This suggested that RBP4 stimulates cancer cell migration along with cell proliferation [28]. Overall, RBP4 could be a negative factor in the response to MSC transplantation, although it is related to cell migration in tumors.…”

Directed Mutation of Two Key Amino Acid Residues Alters the Product Structure of the New 4,6-α-Glucanotransferase from Bacillus sporothermodurans

“…4,6-α-GTs may find application in the fields of the synthesis of dietary fiber, ,, antiretrogradation of starch, , and synthesis of oligosaccharides with the function of immune regulation . In the past decade, only 10 4,6-α-GTs have been characterized, and the catalytic mechanism explaining the products of 4,6-α-GTs with different structures has remained unclear.…”

“…The order of the four motifs in the GtfB-like subfamily sequence is ii−iii−iv−i, which differs from the order of i−ii−iii−iv in the GtfC/D-like subfamily sequence. 4,6-α-GTs may find application in the fields of the synthesis of dietary fiber, 9,14,15 antiretrogradation of starch, 16,17 and synthesis of oligosaccharides with the function of immune regulation. 18 In the past decade, only 10 4,6-α-GTs have been characterized, and the catalytic mechanism explaining the products of 4,6-α-GTs with different structures has remained unclear.…”