earticle

영어

There are three types of alginate lyases: the first type is specific for α-L-guluronate (G) block guluronate lyase, the second type for β-Dmannuronate (M) block mannuronate lyase, and the third type is bifunctional for G and M blocks. These enzymes depolymerize alginate through a β-elimination reaction. Their structure/function relationships are expected to provide information valuable to future industrial alginate processing and drug design for Pseudomonas aeruginosa alginate biofilm-dependent infection. Alginate lyase AlyVI is specific for polyguluronate and has a molecular mass of 34 KDa. Site-directed mutagenesis was used to examine their roles in binding
alginate. Several mutants were prepared, expressed in Escherichia coli, and tested by TBI method using supernatant of culture. Mutants D226K, D226A, and D226G had higher activity than the wild type. Especially, the activities of D226A and D226K were increased nearly 4- and 5-fold, respectively. A relatively conserved tryptophan residue corresponding to tryptophan 165 of alginate lyase AlyVI is proposed to be important for the functioning of the enzyme. Tryptophan 165
was individually changed to an alanine, aspartic acid, arginine, and glycine. All of these mutants were completely inactive. These results indicates that W165 is critical part for enzyme activit