earticle

영어

endo-(1,5)-α-L-Arabinanase (ABN, EC 3.2.1.99) is an endo-acting arabinosyl hydrolase that can cleave α-(1,5)-L-arabinofuranosidic linkages in arabinan and arabinooligosaccharides(AOS). In the present study, a putative gene encoding ABN (LbshABN-B) has been found from the genome of Lactobacillus shenzhenensis LY-73 which is isolated from a dairy beverage in China's Shenzhen market. The open reading frame of LbshABN-B consists of total 1,242 bp nucleotides encoding 414 amino acids with a predicted signal peptide of 24 amino acids. The molecular mass of LbshABN-B without signal peptide is 46.2 kDa. It shares approximately 50% of amino acid sequence identities with the other known ABNs type-B, whereas it showed less than 29% of sequence identities with ABNs type-A. The LbshABN-B gene being fused with six-histidines at its C-terminus was constitutively expressed and purified from Escherichia coli. Although the debranched (linear) arabinan is the most preferred substrate, LbshABN-B showed the significant activity towards sugar beet (branched) arabinan as well. This enzyme showed the highest activity on debranched arabinan at 45oC and pH 6.0 in 50 mM sodium acetate buffer, respectively. LbshABN-B can be applicable to the production of various branched AOS from sugar beet arabinan.