Each of the three lactobacilli tannase genes (i.e. tanLpl, tanLpa, and tanLpe) was expressed as C-terminal His-tag fusion proteins with N-terminal secretion signal peptide which were originating from YbdK protein, which was selected from several clones showed high tannase activity, under the control of aprE promoter in B. subtilis RIK 1285. In all cases, no tannase activity was found in the culture

media, while washed B. subtilis cells showed appreciable activity. Moreover, only after tannase learn more activity appeared in the supernatant of A-769662 manufacturer cultures the lysozyme treatment providing the protoplast, suggesting that the secreted recombinant tannases might be associated with the cell wall. The cells (ca. 1.5 g [wet weight]) were harvested and disrupted by shaking with glass beads prior to purification of the recombinant tannases were purified by the metal affinity chromatography to the purities greater than RepSox cost 95% (Figure 2). Molecular masses of the recombinant TanLpl, TanLpa, and TanLpe were approximately 50 kDa,

50 kDa, and 51 kDa, respectively (Figure 2), which well agreed with the estimation from their respective amino acid sequences. Amino acid sequencing confirmed that the N-terminal sequences of purified TanLpl, TanLpa, and TanLpe matched the corresponding sequence predicted from tanLpl, tanlpa, and tanlpe, respectively. Figure 2 Purification of the recombinant tannase proteins. Proteins were examined by 10%. SDS–PAGE. Lane M, protein molecular-weight markers (labelled in kDa); lane 1, purified TanLpl; lane 2, purified TanLpa; lane 3, purified TanLpe. All recombinant proteins were purified by TALON resin column. Effects of pH, temperature, and

chemicals on tannase activity Enzymatic properties of the lactobacilli tannases were investigated using MG as a substrate. TanLpl and TanLpa showed maximum activities at pH 8.5 and at 40°C, whereas those of TanLpe were optimal at selleck products pH 8.0 and at 35°C (Figure 3a, b). Although TanLpl and TanLpa sustained more than 80% of their enzymatic activities at a pH range of 8.0–10.0, TanLpe drastically lost its activity above pH 9.0. In addition, the activity of TanLpe was always lower than that of TanLpl and TanLpa at temperatures higher than 40°C. In contrast, the activity of A. oryzae tannase showed a maximum level at approximately pH 5.5 and 45–50°C, while it dropped drastically at pH values above 5.5 and below 4.5, but retained more than 50% activity was between 20°C and 60°C (Figure 3a, b). Figure 3 Effects of pH (a) and temperature (b) on the activities of TanLpl (•), TanLpa (□), TanLpe (△), and A. oryzae tannase (×). HPLC analysis was performed under various conditions for the hydrolysis of methyl gallate. pH experiments were performed at 37°C, and temperature experiments were performed at pH 8.0 and 5.5 for lactobacilli tannase and A. oryzae tannase, respectively. The values are shown as the relative activity, and the maximum relative activities are indicated as 100%. Each experiment was performed in triplicate.