초록
A cellulase free thermostable xylanase from Streptomyces sp. CS428 was isolated from a Korean soil sample, purified by single-step chromatography, and biochemically characterized. The extracellular xylanase was purified 26 fold with a 55% yield by CM Trisacryl cation exchange chromatography. The molecular mass of the enzyme (Xyn428) was approximately 37kDa. Xyn428 was found to be stable over a broad pH range (4 to ~13.6) and to 50<SUP>o</SUP>C and have an optimum temperature of 80<SUP>o</SUP>C. Xyn428 had K<SUB>m</SUB> and V<SUB>max</SUB> values of 102.3+/-1.2mg/mL and 3225.4+/-15mmol/minmg, respectively, when beechwood xylan was used as substrate. N-terminal sequence of Xyn428 was INRTDHNENSYLEIHNNEAR. CS428 was grown on different agro waste xylan and produced 4197.1U/mL of xylanase activity in 36h of cultivation in wheat bran without supplements. Xyn428 activity was inhibited by Tris salt at concentrations above 20mM, and produced xylose and xylobiose as major products. It was found to degrade agro waste materials by small unit of enzyme (20U/g) as shown by electron microscopy. As being simple in purification, thermo tolerant, pH stability in broad range and ability to produce xylooligosaccharides show that Xyn428 has potential applications in industries as a biobleaching agent and for xylooligosaccharides production.