원문정보
초록
영어
From the genome of Streptococcus equinus, the putative gene encoding an intracellular α -L-arabinofuranosidase (EC 3.2.1.55, SteqAF43C) has been found, cloned, and constitutively expressed in Escherichia coli. Its open reading frame consists of 1,002 nucleotides encoding 334 amino acids (~38.4 kDa). SteqAF43C with C-terminal six histidines showed the highest activity on debranched arabinan at 30℃ and pH 5.0 in 50 mM sodium acetate buffer. SteqAF43C could exclusively produce L-arabinose from the linear arabinan and linear arabinooligo- saccharides, not from the branched arabinosyl and arabinoxylosyl substrates. These modes of action proposed that SteqAF43C specifically catalyzes the hydrolysis of the α-(1,5)-L-arabinofuranosyl linkages of arabinan backbone, not α-(1,2)/(1,3)-linkages of arabinan branches. Accordingly, SteqAF43C is an arabinan-specific α -(1,5)-L-arabinofuranosidase belonging to GH43.