초록
<P>An alkaline-thermostable mannanase from Streptomyces sp. CS428 was produced, purified, and biochemically characterized. The extracellular mannanase (Mn428) was purified to homogeneity with 12.4 fold, specific activity of 2406.7 U/mg, and final recovery of 37.6 %. The purified beta-mannanase was found to be a monomeric protein with a molecular mass of approximately 35 kDa as analyzed by SDS-PAGE and zymography. The first N-terminal amino acid sequences of mannanase enzyme were HIRNGNHQLPTG. The optimal temperature and pH for enzyme were 60 degrees C and 12.5, respectively. The mannanase activities were significantly affected by the presence of metal ions, modulators, and detergents. K-m and V-max values of Mn428 were 1.01 +/- 3.4 mg/mL and 5029 +/- 85 lmol/min mg, respectively when different concentrations (0.6-10 mg/mL) of locust bean gum galactomannan were used as substrate. The substrate specificity of enzyme showed its highest specificity towards galactomannan which was further hydrolyzed to produce mannose, mannobiose, mannotriose, and a series of mannooligosaccharides. Mannooligosaccharides can be further converted to ethanol production, thus the purified beta-mannanase isolated from Streptomyces sp. CS428 was found to be attractive for biotechnological applications.</P>