Themostable and Acidophilic Arabinose Isomerase and Process for Preparing Tagatose thereby

摘要

PURPOSE: Thermostable and acidophilic arabinose isomerase and a process for preparing tagatose using the same are provided, which recombinant arabinose isomerase has improved acid and heat resistance, prepares tagatose in higher yield under acid condition, and minimize preparation of by-products when tagatose is prepared under acid condition. CONSTITUTION: The thermostable and acidophilic arabinose isomerase has the following properties: (i) optimal temperature of 50 to 80 deg.C, (ii) optimal pH of 5.0 o 7.0, (iii) molecular weight of 56 kDa, and (iv) 50% or more activity at pH 5, wherein the arabinose isomerase is isolated from Alicyclobacillus acidocaldarius. The process for preparing tagatose comprises the steps of: constructing a vector containing the nucleotide sequence set forth in SEQ ID NO: 1 encoding the arabinose isomerase having the amino acid sequence set forth in SEQ ID NO: 2; transforming a host cell with the vector to produce a transformant; culturing the transformant to produce arabinose isomerase; and contacting the arabinose isomerase with galactose at pH 4.0 to 7.0 and 40 to 85 deg.C.