SDS-PAGE analysis of the purification of WcE392-rDSR.

<p>Gel A shows the purification protocol of the enzyme from <i>L. lactis</i> culture supernatant (1). A 2-fold concentrate obtained by ultrafiltration and the ultrafiltration permeate are shown on lanes 2 and 3, respectively. Lane 4 shows the sample eluted from Ni-NTA column. Gel B shows the approximately 60-fold concentrated enzyme sample obtained by ultrafiltration and dilution.</p

Thermal stability of WcE392-rDSR.

<p>The stability was measured in the presence and absence of 0.5% (v/v) glycerol, after incubation at 25°C, 35°C and 40°C for 1, 2, 5 and 24 h.</p

Half-life (<i>t</i>_1/2) of WcE392-rDSR in the presence and absence of glycerol (0.5%, v/v) at various temperatures in 20 mM Na-acetate buffer with 2 mM CaCl₂, pH 5.4.

<p>Half-life (<i>t</i>_1/2) of WcE392-rDSR in the presence and absence of glycerol (0.5%, v/v) at various temperatures in 20 mM Na-acetate buffer with 2 mM CaCl₂, pH 5.4.</p

Predicted protein structure of WcE392-rDSR.

<p>Structural domains A, B, C, VI and V, as presented by Leemhuis et al.[<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116418#pone.0116418.ref001" target="_blank">1</a>], are shown separated by dotted lines.</p

Enzymatic production of dextran into wheat bran.

<p>Composition of runs of the experimental design and the final dextran contents. Sucrose, fructose and dextran contents are given as a percentage of dry weight (dw-%). A hyphen (-) denotes that the values were below the detection limit.</p><p>Enzymatic production of dextran into wheat bran.</p

Influence of the sucrose and water contents in the initial reaction mixture and the incubation time on final dextran content in the experimental series shown as contour plots.

<p>Dextran production is enhanced by higher sugar content. In the 2 h plot, higher water content clearly increases dextran production but in the 4 h plot the effect can only be seen with higher sucrose content and in the 6 h plot the effect is completely muted. The quadratic effect of incubation time shows as highest dextran contents in the 4 h plot. Dextran amount is given as a percentage of dry weight.</p

Compositions of the doughs used for studying the effects of bran with dextran on bread properties.

<p>Compositions of the doughs used for studying the effects of bran with dextran on bread properties.</p

Effects of pH and temperature on WcE392-rDSR activity.

<p>Effect of pH was assayed in 20 mM Na-acetate (pH 4 to 6) and in 20 mM Tris-HCl (pH 6.5 to 7.0), and the effect of temperature in 20 mM Na-acetate, pH 5.4. Reactions were incubated for 15 min. The reaction mixtures were supplemented with 2 mM CaCl₂ and the Nelson-Somogyi method was used for assaying the activities. Error bars represent the standard errors of the mean (n = 3).</p

Specific activities and kinetic values of WcE392-rDSR.

<p>Specific activities and kinetic values of WcE392-rDSR.</p

Optimization of Isomaltooligosaccharide Size Distribution by Acceptor Reaction of Weissella confusa Dextransucrase and Characterization of Novel α‑(1→2)-Branched Isomaltooligosaccharides

Long-chain isomaltooligosaccharides (IMOs) are promising prebiotics. IMOs were produced by a Weissella confusa dextransucrase via maltose acceptor reaction. The inputs of substrates (i.e., sucrose and maltose, 0.15–1 M) and dextransucrase (1–10 U/g sucrose) were used to control IMO yield and profile. According to response surface modeling, 1 M sucrose and 0.5 M maltose were optimal for the synthesis of longer IMOs, whereas the dextransucrase dosage showed no significant effect. In addition to the principal linear IMOs, a homologous series of minor IMOs were also produced from maltose. As identified by MS^<i>n</i> and NMR spectroscopy, the minor trisaccharide contained an α-(1→2)-linked glucosyl residue on the reducing residue of maltose and thus was α-d-glucopyranosyl-(1→2)-[α-d-glucopyranosyl-(1→4)]-d-glucopyranose (centose). The higher members of the series were probably formed by the attachment of a single unit branch to linear IMOs. This is the first report of such α-(1→2)-branched IMOs produced from maltose by a dextransucrase