원문정보
초록
영어
Polyguluronate specific lyase (EC 4.2.2.11) from Streptomyces sp.
ALG-5 was cloned in pColdI vector and characterized previously. We named the polyG-specific lyase as ALG5 lyase. Alg5 was engineered to improve the alginate degrading activity based on comparative homology modeling. The homology modeling of ALG5 lyase was constructed by using the 3D crystal structure (1UAI.pdb) of alginate lyase 2 from Corynebacterium sp. Aly1 as a template. ALG5 lyase belongs to polysaccharide lyase family 7 which the fold of the structure is β-jolly sandwich. ALG5 lyase had 8 β-strands (SA1-SA8)at upper layer and 7 β-strands (SB1-SB7) at lower layer. Active sites were formed with Arg72 of SA3, Gln117 of SA5, His119 of SA5, Tyr188 of SA4 and Tyr194 of SA5. In the case of water soluble protein, protein surface was known to be composed with hydrophilic amino acid residues whereas protein core was composed with hydrophobic amino acid residues. Stability of mutants was calculated with ProSa2003.
Glu101 on SB4 was mutated to hydrophobic amino acid, Phe, Leu, Met, Ile and Val. When Glu101 was mutated to Leucine, the alginate degrading activity was increased about 5 fold than that of original ALG5 lyase.