| 초록 |
A new endo-1,4-beta-xylanase gene (FJ380951), KRICT PX1, isolated from Paenibacillus sp. HPL-001, was expressed in E. coli. Enzyme purification, mutation, immobilization, and molecular simulation were conducted. The P1H1 mutant of one amino acid substitution (168Leu￫Gln) showing the strongest xylanase activity was selected among 250 mutant clones. The specific activity of the P1H1 xylanase was 53.3 U/mg protein at 50°C, an approximately fivefold increase compared to that of the original KRICT PX1 xylanase (10.25 U/mg protein) at the same condition of pH 5~10, and enhanced activity from 20.1 to 36.6 U/mg proteins at 60°C. The structural dynamics of the mutant P1H1 became stronger than that of the wild type, which could be eliminated by a helix deformation with the H-bond missing between Leu168 and Asp164 after mutation. Xylanase could be reused for 5 batches without significant loss of activity after being immobilized on surface functionalized silica-based mesoporous cellular foam. However, xylanase activity declined to 60% at the 10th batch. Further research on practical applications will be necessary for industrial usage. |
