A moderately thermostable Glucansucrase (4,6-Alpha-Glucanotransferase, reuteransucrase). The enzyme transfers glucose units from sucrose to make a highly branched, high molecular weight alpha-D-Glucan with α(1→4) glucosidic linkages and also some α(1→6) linked glucosyl units.
The enzyme is available for purchase as 100 or 500 microliter solution (1 mg/ml).
Product Gtfa163S | 100 microliter | EUR 195
Product Gtfa163L | 500 microliter | EUR 490
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Enzyme activity: Gtfa163 Glucansucrase (Reuteransucrase) catalyses the transfer of glucose from sucrose to make a highly branched, high-molecular-weight α-D-glucan with α(1→4) glucosidic linkages but also some α(1→6)-linked glucosyl units and 4,6-disubstituted glucosyl units at the branching points.
As an example, glucose transferase activity was determined at 50°C for 60 hours in a 25 mM sodium acetate buffer at pH 4.7, containing 1 mM CaCl2 and 100 mM sucrose. This gave complete utilization of the sucrose with about 75% going into α-D-glucan.
Activity determination: Glucansucrase activity was determined at 50°C in a 25 mM sodium acetate buffer at pH 4.7, containing 10 mM CaCl2 and 30 nM enzyme.
Unit definition: One unit (U) of enzyme activity is the amount that leads to the release of 1 μmol of fructose from sucrose per minute.
Synonyms: glycoside hydrolase, glucosyltransferase, 4,6-alpha-Glucanotransferase, Reuteransucrase
Protein family: Glycosyl hydrolase family 70 ( GH70 ) – GH-H clan – CAZy database GH70 family
Source: The lactic acid bacteria Lactobacillus reuteri strain 121
Protein sequence: NBCI protein entry
Structural information: The crystal structure of Gtfa163 Glucansucrase (Reuteransucrase) from Lactobacillus reuteri121 has been determined and shown here in Figure 1 (Pijning et al. 2012). – PDB entry 4AMC
Figure 1: Crystal structure of Gtfa163 Glucansucrase
(truncated form comprising residues 745-1763 including catalytic domain)
The enzyme produced a α-D-glucan polymer (MW 3.5×106 Da) with a composite structure, that includes all identified structural elements, as shown in Fig. 2 below (van Leeuwen et al 2008)
Figure 2. Composite model of a alpha-D-glucan product made by Gtfa163 Glucansucrase
Oligosaccharides from sucrose:
With only sucrose present, and before branching starts, the enzyme activity will yield a linear oligosaccharides via alternating α(1→4) and α(1→6) linkages. Malto-oligosaccharides (DP2-DP6) in the absence of sucrose are slow substrates. With high concentration of sucrose the formation of low-molecular-mass oligosaccharides was favoured over high-molecular-mass polysaccharides.
Properties of Gtfa163 Glucansucrase:
Figure 4. pH profile: Solid line, transferase activity; dashed line, hydrolysis activity (Kralj et al. 2004).
Van Leeuwen SS, Kralj S, van Geel-Schutten IH, Gerwig GJ, Dijkhuizen L, Kamerling JP (2008) Structural analysis of the α-D-glucan (EPS35-5) produced by the Lactobacillus reuteri strain 35-5 glucansucrase GTFA enzyme. Carbohydr. Res. 343: 1251–1265.
Kralj S, van Geel-Schutten GH, van der Maarel MJEC & Dijkhuizen L (2004) Biochemical and molecular characterization of Lactobacillus reuteri 121 reuteransucrase. Microbiology 150: 2099–2112.
Leemhuis H, Pijning T, Dobruchowska JM, van Leeuwen SS, Kralj S, Dijkstra BW, Dijkhuizen L. (2013) Glucansucrases: Three-dimensional structures, reactions, mechanism, α-glucan analysis and their implications in biotechnology and food applications. J. Biotechnol. 163:250-272.
Pijning T, Vujicic-Zagar A, Kralj S, Dijkhuizen L & Dijkstra BW (2012) Structure of the α-1,6/α-1,4-specific glucansucrase GTFA fromLactobacillus reuteri 121. Acta Cryst. F68: 1448-1454.