Characterization of a novel GH2 family α-L-arabinofuranosidase from hyperthermophilic bacterium Thermotoga thermarum.

The 2,367-bp ORF of TtAFase from Thermotoga thermarum DSM 5069 encodes a calculated 90-kDa α-L-arabinofuranosidase (TtAFase), which does not belonging to any reported glycosyl hydrolase families α-L-arabinofuranosidases in the database and represents a novel one of glycosyl hydrolase family 2. The purified recombinant TtAFase produced in Escherichia coli BL21 (DE3) had optimum activity at pH 5.5 and at 80 °C. It was stable up to 80 °C and from pH 4.5-8.5. Kinetic experiments at 80 °C with p-nitrophenyl α-L-arabinofuranoside as a substrate gave a K m of 0.77 mM, V max of 2.3 μmol mg(-1) min(-1) and k cat of 4.5 s(-1). The enzyme had no apparent requirement of metal ions for activity, and its activity was significantly inhibited by Cu(2+) or Zn(2+).