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Catalytically important amino-acid residues of abalone alginate lyase HdAly assessed by site-directed mutagenesis

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Title: Catalytically important amino-acid residues of abalone alginate lyase HdAly assessed by site-directed mutagenesis
Authors: Yamamoto, Sayo Browse this author
Sahara, Takehiko Browse this author
Sato, Daisuke Browse this author
Kawasaki, Kosei Browse this author
Ohgiya, Satoru Browse this author
Inoue, Akira Browse this author →KAKEN DB
Ojima, Takao Browse this author →KAKEN DB
Keywords: alginate lyase
abalone
Haliotis discus hannai
cold-inducible expression in yeast
recombinant enzyme
site-directed mutagenesis
Issue Date: 6-Nov-2008
Publisher: Elsevier
Journal Title: Enzyme and Microbial Technology
Volume: 43
Issue: 6
Start Page: 396
End Page: 402
Publisher DOI: 10.1016/j.enzmictec.2008.06.006
Abstract: Alginate lyase is an enzyme that degrades alginate chains via β-elimination and has been used for the production of alginate oligosaccharides and protoplasts from brown algae. Previously, we deduced the amino-acid sequence of an abalone alginate lyase, HdAly, from its cDNA sequence and, through multiple amino-acid sequence alignment, found that several basic amino-acid residues were highly conserved among the polysaccharide-lyase family 14 (PL-14) enzymes including HdAly. In the present study, we assessed the functional importance of the conserved basic amino-acid residues in HdAly by using sitedirected mutants that were produced with a cold-inducible yeast expression system consisting of an expression vector pLTex321sV5H and a host Saccharomyces cerevisiae BY4743. At first, we prepared wildtype HdAly with the yeast expression system and confirmed that this recombinant possesses nearly the same properties as native HdAly with respect to specific activity (1300 U/mg), optimal pH (7.8), optimal temperature (35℃), and protoplast-producing ability from the brown alga Laminaria japonica. Then, we prepared a series of site-directed mutants by replacing the conserved basic amino-acid residues of HdAly with Ala and determined the alginate-degrading activity of these mutants. As a result, we found that the replacement of Lys95 caused complete inactivation of HdAly and those of Arg92, Arg110, and Arg119 caused 65% or more inactivation. These results indicate that the region spanning Arg92 to Arg119 is closely related to the catalytic activity of HdAly.
Type: article (author version)
URI: http://hdl.handle.net/2115/38497
Appears in Collections:水産科学院・水産科学研究院 (Graduate School of Fisheries Sciences / Faculty of Fisheries Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 尾島 孝男

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