Characteristics of α-L-arabinofuranosidase from Streptomyces sp I10-1 for production of L-arabinose from corn hull arabinoxylan.

Streptomyces sp I10-1 α-L-arabinofuranosidase efficiently produced L-arabinose from high arabinose-content corn hull arabinoxylan (ratio of arabinose to xylose, 0.6). The optimum pH at 40 °C was around 6, and the enzyme was stable from pH 5 to 11. The optimum temperature was 50 °C at pH 5, and the activity was stable at 40 °C. The enzymatic activity against corn hull arabinoxylan was 2.3 times higher than towards p-nitrophenyl-α-L-arabinofuranoside. Approximately 45% L-arabinose recovery was achieved from corn hull arabinoxylan. It was considered that L-arabinose residues not removed by the enzyme were attributable to those linked with ferulic acid. The open reading frame of the enzyme gene consisted of 1,224 bp, and the predicted peptide was 408 amino acids, which corresponded to a molecular size of 45, 248 Da. It was presumed that the smaller molecular size (31,000 Da) estimated on SDS-PAGE resulted from proteolysis by proteases. I10-1 α-L-arabinofuranosidase belongs to the Alpha-L-AF C superfamily, which is associated with glycoside hydrolase family 51, but the properties were unique.