Escherichia coli BL21 (Promega) was used for protein purification and was grown anaerobically in 2 × TY (Difco) supplemented with ampicillin (100 μg mL−1) at 37 °C. The sequence of the tnaA gene and flanking regions in the type strain of P. intermedia ATCC 25611 was determined by gene walking with primers designed on basis of the whole-genome sequence of P. intermedia strain 17 (http://www.oralgen.lanl.gov/oralgen/bacteria/pintnew/). selleck compound RT-PCR analysis was carried out as described previously (Yoshida et al., 2003). Briefly, RNA was reverse-transcribed into single-stranded cDNA with random hexadeoxyribonucleotide primers

(Takara Bio) using PrimeScript Reverse Transcriptase (Takara Bio) according to the manufacturer’s instructions. The gene-specific primers used in RT-PCR are listed in Supporting information, Table S1. The locations of the gene-specific primers used for RT-PCR

are indicated in Fig. 1. Reaction mixtures without reverse transcriptase were used as negative controls to evaluate the presence of contaminating genomic DNA in the samples. Recombinant TnaA from P. intermedia ATCC 25611 was expressed and purified using the expression vector pGEX-6P-1 (GE Healthcare), as described previously (Yoshida et al., 2002). The tnaA gene was PCR-amplified using the primers designed to incorporate a BamHI site at the 5′ end and a SalI site at the 3′ end of each segment (Table S1). Following amplification, the products Z-VAD-FMK datasheet were digested with the appropriate restriction enzymes and ligated into pGEX-6P-1, juxtaposing the tnaA fragment downstream of the coding sequence for glutathione S-transferase and a PreScission protease (GE Healthcare) cleavage site. The purity of the protein Montelukast Sodium samples was confirmed by SDS-PAGE. The molecular weight of recombinant purified TnaA was determined by gel-filtration chromatography using

a Superdex 200 HR 16/60 column (GE Healthcare) at a flow rate of 1.0 mL min−1 in 20 mM potassium phosphate buffer (pH 7.5). For this procedure, a standard curve was produced using molecular weight standards. Enzyme elution was monitored at 280 nm. l-Tryptophan degradation by purified tryptophanase was examined by measuring indole formation, as reported previously (Morino & Snell, 1970; Sasaki-Imamura et al., 2010). Briefly, after layering the reaction mixture [200 mM potassium buffer (pH 7.5), 0.165 mM pyridoxal-5′-phosphate (PLP), 0.2 mM reduced glutathione, 0.25 mg mL−1 bovine serum albumin, 10 μg mL−1 purified tryptophanase, and several concentrations of l-tryptophan] with 100 μL of toluene, the reaction mixture was prewarmed for 5 min at 37 °C. After a 10-min incubation period, the reaction was terminated by the addition of 1 mL of Ehrlich’s reagent, which was prepared daily by mixing five volumes of 5% (w/v) p-dimethylaminobenzaldehyde in 95% (v/v) ethanol with 12 volumes of 5% (v/v) H2SO4 in 1-butanol. The supernatant was examined spectrophotometrically at 568 nm.